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May 1982

Volume 21, Issue 1, pp. 1-262


Growth of lead‐germanium‐telluride thin film structures by molecular beam epitaxy

D. L. Partin

J. Vac. Sci. Technol. 21, 1 (1982); http://dx.doi.org/10.1116/1.571714 (5 pages) | Cited 15 times

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The development of Pb1−xGexTe devices would extend the total wavelength range that can be covered by tunable diode lasers. Pb1−xGexTe was grown from PbTe, GeTe, and Te sources at 2 μm/h and in vacuums <10−8 Torr. The Ge concentration as a function of depth in the grown layers was measured with Auger electron spectroscopy in combination with argon ion sputtering. GeTe segregates on the surface for substrate growth temperatures of 220 °C and below, and preferentially evaporates at 330 °C. Heat treatment of PbTe/Pb1−xGexTe superlattice structures with 200 Å periodicity yields a Ge diffusion coefficient of 2×10−18 cm2/s at 270 °C. The effect of lattice mismatch on crystal quality was determined from etch pit density studies. PbTe/ Pb1−xGexTe/PbTe structures with thin intermediate layers had much lower etch pit densities than thicker films, in good agreement with theory.
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68.55.-a Thin film structure and morphology
68.60.-p Physical properties of thin films, nonelectronic
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Surface and contact properties of GaAs overlaid by silver

J. M. Palau, E. Testemale, A. Ismail, and L. Lassabatere

J. Vac. Sci. Technol. 21, 6 (1982); http://dx.doi.org/10.1116/1.571739 (8 pages) | Cited 3 times

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A study was made of the Schottky barrier formation on cleaved n‐ and p‐type GaAs through surface and contact measurements. The metal used was silver. Surface studies, performed using the Kelvin method, have revealed that pinning of the Fermi level is obtained at submonolayer coverage and that silver deposition induced modifications in the electronic affinity. An electrical study of the contacts showed that diffusion barrier eVD is in the 950‐meV range for the n type and in the 270‐meV range for the p type. The difference between the pinning levels of n and p types for submonolayer coverage was found to be equal to that for contacts. We deduced that the Schottky barrier is established as soon as the first silver atoms are deposited. Possible characteristics were calculated for surface states (assumed to be discrete).
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73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Ns Metal-nonmetal contacts

TiN formed by evaporation as a diffusion barrier between Al and Si

C. Y. Ting

J. Vac. Sci. Technol. 21, 14 (1982); http://dx.doi.org/10.1116/1.571700 (5 pages) | Cited 35 times

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The formation of TiN thin films by doping Ti with N2 during evaporation at room temperature and by following with high‐temperature (700–900 °C) annealing was confirmed by x‐ray analysis. This is different from conventional reactive sputtering and is compatible with lift‐off processes in pattern delineation. It has been observed that when Ti is heavily doped with N on a silicon substrate, the reaction between Ti and Si which forms TiSi2 is totally suppressed during high‐temperature annealing and forms TiN only. On the other hand, if a thin layer of pure Ti was evaporated on a Si substrate before the introduction of N2, then a composite film of TiN/TiSi2 was formed with a clear boundary between them after high‐temperature annealing. The thickness of each layer can be well controlled by the initial evaporation thickness. In both cases, Al was deposited on top. Rutherford backscattering studies showed that TiN is an effective diffusion barrier up to 550 °C for 30 min of annealing and forms an ideal contact barrier between Al and Si.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Grain boundary diffusion of phosphorus in polycrystalline silicon

P. H. Holloway

J. Vac. Sci. Technol. 21, 19 (1982); http://dx.doi.org/10.1116/1.571713 (4 pages) | Cited 13 times

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The preferential diffusion of phosphorus down grain boundaries in cast polysilicon wafers has been studied using angle polishing followed by measuring junction depth by staining or e‐beam†induced current. Data show that at 1040 °C the grain boundary diffusion parameter is 8000 × larger than the bulk diffusion coefficient (DBulk = 3.3×10−13cm2/s). During normal diffusion for 40 min at 1040 °C, a junction was created at 1.8 μm within the grain itself, but at the grain boundary the junction region extended ∠6 μm into the wafer. Concentration profiles near the grain boundary were calculated and compared to electrical response data for similar grain boundaries. In addition, the effects of heating polycrystalline wafers without a source of phosphorus at the surface was calculated, and it was concluded that lateral inhomogeneities of the dopant concentration, which may degrade solar cell performance, will exist both with and without a constant source of phosphorus for diffusion.
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66.30.Lw Diffusion of other defects
61.72.Mm Grain and twin boundaries
84.60.Jt Photoelectric conversion

Photodeposition of metal films with ultraviolet laser light

D. J. Ehrlich, R. M. Osgood, and T. F. Deutsch

J. Vac. Sci. Technol. 21, 23 (1982); http://dx.doi.org/10.1116/1.571724 (10 pages) | Cited 34 times

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A technique for maskless writing of metal films with submicrometer dimensions is described. An ultraviolet beam from a cw or pulsed laser is used to photodissociate an organometallic gas near a gas–solid interface. The liberated metal atoms then condense in an area of dimensions comparable to the laser spot size. Experiments which elucidate the essential physics of the process have been performed.
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68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Trilevel lift‐off process for refractory metals

P. Grabbe, E. L. Hu, and R. E. Howard

J. Vac. Sci. Technol. 21, 33 (1982); http://dx.doi.org/10.1116/1.571731 (3 pages) | Cited 2 times

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A trilevel lift‐off process is described which incorporates a high‐glass‐temperature polymer, polyimide. This process allows the high resolution patterning of refractory materials at elevated substrate temperatures (≳200 °C). It has been successfully used to produce patterned superconducting niobium films whose critical temperatures suffered no degradation compared to simultaneously evaporated, unpatterned films.
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81.05.Je Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.65.-b Surface treatments

Auger and x‐ray characterization of surface nitride films on Ti, Zr, and Hf

P. T. Dawson and S. A. J. Stazyk

J. Vac. Sci. Technol. 21, 36 (1982); http://dx.doi.org/10.1116/1.571732 (6 pages) | Cited 3 times

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Polycrystalline discs of Ti, Zr, and Hf have been nitrided by RF heating to 925, 1200, and 925 °C in flowing NH3 gas at 300 Torr. The surface films are characterized by Auger electron spectroscopy using argon ion sputtering to determine the composition depth profiles and by x‐ray diffraction to identify the phases present. The depth profiles have characteristic features consistent with the phases identified by x‐ray diffraction: Cubic TiN, tetragonal Ti2N and hexagonal α‐Ti, cubic ZrN and hexagonal α‐Zr, and α‐Hf N solid solutions. The Hf nitride surface phase was too thin to be detected by x‐rays. A semiquantitative analysis of Auger intensities is described utilizing the composition of the phases identified by x‐ray diffraction.
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68.55.-a Thin film structure and morphology
68.60.-p Physical properties of thin films, nonelectronic
82.39.Wj Ion exchange, dialysis, osmosis, electro-osmosis, membrane processes

Effects of the experimental parameters on the preferred orientation of chemically vapor deposited TiC on cemented carbides

C. W. Lee, S. W. Nam, and John S. Chun

J. Vac. Sci. Technol. 21, 42 (1982); http://dx.doi.org/10.1116/1.571733 (5 pages) | Cited 3 times

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The relation between the preferred orientation, microhardness, and microstructure of TiC coatings was studied for various deposition conditions. The coatings deposited at 1000 °C showed 〈111〉 preferred orientation and finer equiaxed grains, resulting in high microhardness values. High microhardness values were also obtained with a decrease in total pressure. Coatings deposited above 1100 °C showed 〈110〉 preferred orientation and coarser elongated grains which results in lower microhardness values.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
68.35.Gy Mechanical properties; surface strains
68.35.Iv Acoustical properties
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics

Angle‐resolved photoemission studies of oxide formation on Cu(100)

D. T. Ling, J. N. Miller, P. Pianetta, D. L. Weissman, I. Lindau, and W. E. Spicer

J. Vac. Sci. Technol. 21, 47 (1982); http://dx.doi.org/10.1116/1.571734 (3 pages) | Cited 2 times

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We performed ARPES studies of the oxidation of Cu(100). The results are in agreement with a model where oxygen chemisorption above the surface is followed by incorporation into the bulk and finally copper (I) oxide formation. The spectra obtained for Cu2O show little angular anisotropy. They are in good agreement with earlier angle‐integrated measurements of Evans using a polycrystalline sample and ARPES measurements of Lloyd, Quinn, and Richardson also using Cu(100). However, the latter authors appear to have misplaced the Fermi level in their spectra.
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81.05.Bx Metals, semimetals, and alloys
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Passivation of carbon steel using low energy mercury ion surface treatment

R. S. Robinson and P. J. Wilbur

J. Vac. Sci. Technol. 21, 50 (1982); http://dx.doi.org/10.1116/1.571735 (6 pages)

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An experimental study is described, in which carbon steel samples were bombarded with low‐energy mercury ions from a broad beam ion source and their subsequent corrosion characteristics in air were evaluated. Mercury ion doses of a few mA⋅min/cm2 at energies of a few hundred electron volts are shown to effect significant improvements in the corrosion resistance of the treated steel surfaces. In a warm, moist environment, the time before the onset of significant corrosion was increased more than two orders of magnitude from 15 min for an untreated sample to ∠30 h for a sample implanted with 33 mA⋅min/cm2 of 1000 eV mercury ions.
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81.05.Bx Metals, semimetals, and alloys
61.72.U- Doping and impurity implantation

The ’’cover up’’ of particles by substrate material during ion beam sputtering

J. L. Hock, D. Snider, R. Ford, and D. Lichtman

J. Vac. Sci. Technol. 21, 56 (1982); http://dx.doi.org/10.1116/1.571736 (5 pages)

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The problems associated with the contamination of particle surfaces by the support material when ion sputtering is used as a method of depth profiling individual particles in an AES study are described. Initial observations indicated that if particles are mounted on an indium substrate, then after relatively short periods of argon ion beam sputtering the particle becomes completely obscured for Auger analysis by indium. The effects of varying different parameters: argon gas pressure, angle of both the ion beam and the analyzing electron beam, the morphology of the particle, and a selection of different metal substrates are reported. It is believed that the phenomenon is caused by a direct scattering process and not backscattering from the gas phase or surface migration. The conclusion is that even if highly refractory metals, e.g., tungsten, are used as the substrate, there is little that optimization of the different parameters described can do to reduce this very serious effect. These results bring into question the validity of undertaking such measurements unless the ion beam profile is reduced to dimensions below that of the particle being analyzed.
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79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
79.20.Fv Electron impact: Auger emission

Columnar etching residue generation in reactive sputter etching of SiO2 and PSG

Y. Ozaki and K. Hirata

J. Vac. Sci. Technol. 21, 61 (1982); http://dx.doi.org/10.1116/1.571737 (5 pages) | Cited 3 times

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The generation mechanism and structure of columnar etching residues generated in reactive sputter etching of SiO2 and PSG using CF4+H2 are investigated. The slight resist scum, remaining after the resist development step, promotes plasma polymerization. The polymerized film thus formed plays the role of an etching mask, resulting in columnar etching residue generation. These residues are SiO2 and PSG covered with a plasma polymerized film.
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81.65.-b Surface treatments

Cylindrical magnetron co‐sputter etching of copper tubes with applications for solar selective absorbing surfaces

M. R. Lake and G. L. Harding

J. Vac. Sci. Technol. 21, 66 (1982); http://dx.doi.org/10.1116/1.571738 (4 pages) | Cited 1 time

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The surfaces of copper tubes have been uniformly textured by co‐sputter etching in a cylindrical magnetron using titanium seed. The variation of surface morphology as a function of sputter etching conditions has been studied. Trends are similar to those observed in previous experiments on the sputter etching of plane copper sheet. The textured surfaces may be utilized as selective absorbing surfaces in the solar thermal collectors. Typical surfaces produced have absorptances α = 0.94 and emittance ϵ = 0.13 at 300 K.
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81.05.Bx Metals, semimetals, and alloys

’’Hot’’ atom interactions with polymer surfaces

J. M. Burkstrand

J. Vac. Sci. Technol. 21, 70 (1982); http://dx.doi.org/10.1116/1.571740 (4 pages) | Cited 1 time

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Sputter deposition of metal films is being used more widely in the industrial sector for the coating of many materials. In an effort to identify interface chemical bonds, if any, the interactions of sputter‐deposited (’’hot’’) Ni atoms with polyvinyl alcohol (PVA), polyvinyl methyl ether (PVME), polymethyl methacrylate (PMMA), and polyvinyl acetate (PVAC) surfaces have been investigated using x‐ray photoemission spectroscopy (XPS). Nickel atoms and ions resulting from the bombardment of clean Ni foil by 1000‐eV argon ions were impinged normally on clean polymer surfaces. At Ni coverages of about one third monolayer or more on both PVA and PVME, a new peak in the oxygen 1s core level spectrum was observed which had a binding energy 1.7 eV smaller than the original bulk polymer oxygen. The resulting Ni complex can be contrasted to that formed when thermally evaporated Ni atoms interact with the same surface. In the latter, a Ni–O–C chelate complex was formed having a new oxygen 1s binding energy 1.3 eV smaller than the bulk. This difference implies that the hot or sputter‐deposited Ni atoms are more strongly bound to the oxygen than they are in the chelate complexes produced by thermally evaporated Ni. The interactions of the hot Ni atoms with the more complex PMMA and PVAC are more difficult to interpret. On these polymer surfaces, XPS cannot distinguish between metal complexes formed by evaporation and those complexes formed by sputtering.
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82.30.-b Specific chemical reactions; reaction mechanisms
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
79.60.Jv Interfaces; heterostructures; nanostructures

The interface orientation of perylene red and phthalocyanine molecules vapor deposited on aluminum

Mark K. Debe

J. Vac. Sci. Technol. 21, 74 (1982); http://dx.doi.org/10.1116/1.571741 (6 pages) | Cited 2 times

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Reflection absorption infrared (RAIR) spectroscopy has been used to study thin films of photo‐sensitizing dyes deposited by vacuum sublimation onto aluminum. Strong monotonic variations in relative band absorbances were observed for perylene red films of varying thicknesses (from 1400 to 30 Å) sublimed onto air‐oxidized vapor‐deposited aluminum substrates. Normalizing to constant film thickness, the bands with dipole transition moments perpendicular to the major symmetry plane of the molecule strongly attenuate as the interface is approached. Those with moments parallel to the major symmetry axis double in intensity while those in the third direction remain constant. The RAIR selection rule that only dipole moment changes normal to the surface can be seen implies, then, that at the interface the perylene red molecules are preferentially oriented and standing one‐third on edge and two‐thirds on end but none flat‐on. This behavior is in contrast to that observed from similarly deposited films of metal‐free phthalocyanine which appear to remain disordered as film thickness decreases. Comparison with recent three‐dimensional x‐ray‐produced crystal structures for perylene red and the role of the substrate are discussed.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Fourier transform reflection infrared spectroscopy of adsorbed species: Instrumental considerations

M. J. Dignam and M. D. Baker

J. Vac. Sci. Technol. 21, 80 (1982); http://dx.doi.org/10.1116/1.571742 (6 pages)

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An analysis of the factors limiting the sensitivity of Fourier Transform Infrared (FT–IR) spectroscopy as applied primarily to reflectance vibrational spectra of adsorbed species, but also to vibrational circular dichroism, is presented, along with methods of overcoming these. A particularly promising approach involves the use of a polarizing Michelson interferometer (PMI) and a multichannel detection system, a combination that should give a sensitivity improvement of at least tenfold over the best instruments currently available. An outline of a possible optical scheme for a high‐sensitivity FT–IR system for reflectance spectroscopy is given involving a PMI and orthogonal reflections from a test and reference surface.
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07.57.Ty Infrared spectrometers, auxiliary equipment, and techniques

Experimental investigation of flow characteristics and thermal accommodation in neutralizer gas cells

Johann L. Hemmerich and Eduard B. Deksnis

J. Vac. Sci. Technol. 21, 86 (1982); http://dx.doi.org/10.1116/1.571743 (5 pages)

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We have performed conductance measurements on 1/10 scale models of typical neutralizer gas cells, both round (32 mm i.d.×163 mm length) and rectangular (20×50 mm cross section×95 mm length). The gas inlet temperature was kept constant at room temperature (295 K), while the duct models were temperature variable (from 77 to 700 K). It could be shown that (1) the gas fully thermally accommodates to duct wall temperature; (2) under typical operating conditions, i.e., for gas target thicknesses from 3×1015 to 1×1016 molecules per cm2, the flow characteristics are dominated by the temperature dependent viscous component. An empirical relation describing the temperature dependence is given. A consequent application of the effects observed leads to improvements in neutralizer performance: if, e.g., a section cooled to 77 K is followed by a section heated to 700 K, the gas flow required for a given gas target thickness is about a factor of 3 lower compared to both sections being at 300 K.
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47.60.-i Flow phenomena in quasi-one-dimensional systems
47.70.-n Reactive and radiative flows
51.30.+i Thermodynamic properties, equations of state

Direct heating of a rod cathode through balanced current feeders

T. Kishi and T. Takagi

J. Vac. Sci. Technol. 21, 91 (1982); http://dx.doi.org/10.1116/1.571662 (4 pages) | Cited 3 times

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A directly heated Ta rod cathode diam = 0.8 mm, which was fed dc current through small contact areas of a few knife‐edge, fan‐shaped W current feeders symmetrically supported near the emitting end of the rod, is studied. An electron beam from a gun made of such cathode structure is free from the effects of the magnetic fields produced by the heating current when the cathode is heated to 2000 K and the current through two feeders is 26 A. An optimum contact area at the supporting point is obtained from a one‐dimensional heat equation in the current feeder. A typical brightness value for this gun is of the order of 5×102 A/cm2 for the electron beam of 2 mA at 4 kV. The average lifetime of the cathode is not less than 60 h.
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84.47.+w Vacuum tubes

The measurement and calculation of loop temperatures in an FIM

H. Morikawa, M. Kozakai, T. Terao, and Y. Yashiro

J. Vac. Sci. Technol. 21, 95 (1982); http://dx.doi.org/10.1116/1.571663 (5 pages)

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A tip for FIM was made of various kinds of metals in order to monitor the tip temperature. A conventional four‐terminal method was used to measure the average temperature of the loop at the instant the tip melted. A computer calculation has also been carried out to obtain the temperature distribution in the loop and tip. The tip‐base temperature was obtained by matching the calculated loop resistance to the measured resistance. Finally, the calculated tip‐base temperature agreed well with the melting points of the tip materials to an accuracy of better than 99%.
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07.20.Ka High-temperature instrumentation; pyrometers
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Erratum: A report from the AVS Standards Committee: Comparison of ion gauge calibrations by several standards laboratories [J. Vac. Sci. Technol. 20, 75 (1982)]

I. Warshawsky

J. Vac. Sci. Technol. 21, 100 (1982); http://dx.doi.org/10.1116/1.571685 (1 page)

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Abstract Unavailable
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07.30.Dz Vacuum gauges
06.20.F- Units and standards
99.10.Cd Errata

Erratum: Shallow and parallel silicide contacts [J. Vac. Sci. Technol. 19, 766 (1982)]

K. N. Tu

J. Vac. Sci. Technol. 21, 100 (1982); http://dx.doi.org/10.1116/1.571686 (1 page)

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Abstract Unavailable
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84.32.Dd Connectors, relays, and switches
85.30.Hi Surface barrier, boundary, and point contact devices
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
73.40.Ns Metal-nonmetal contacts
99.10.Cd Errata

Simple spot photometer for LEED intensity measurements

A. G. Schrott, M. D. Chinn, C. G. Shaw, and S. C. Fain

J. Vac. Sci. Technol. 21, 101 (1982); http://dx.doi.org/10.1116/1.571687 (1 page) | Cited 1 time

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A low cost photometer is described which is intended to be used in conjunction with voltage modulation of the LEED suppressor grid.
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07.60.Dq Photometers, radiometers, and colorimeters
61.05.jh Low-energy electron diffraction (LEED) and reflection high-energy electron diffraction (RHEED)

A graphite crucible for spitting‐free high rate e‐gun evaporation of Ge

M. L. Rappaport and B. Berkovitz

J. Vac. Sci. Technol. 21, 102 (1982); http://dx.doi.org/10.1116/1.571688 (1 page) | Cited 1 time

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A design for a crucible is reported which completely eliminated explosions and splitting when used with a Sloan BXV‐6 gun.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
84.47.+w Vacuum tubes

Vertical motion mount for a quadrupole prefilter

R. D. Schmidt and J. H. Craig

J. Vac. Sci. Technol. 21, 103 (1982); http://dx.doi.org/10.1116/1.571689 (2 pages)

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Abstract Unavailable
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07.75.+h Mass spectrometers

An improved method for long‐term automatic operation of titanium sublimation pumps in ultra high vacuum

R. K. MacNabb

J. Vac. Sci. Technol. 21, 105 (1982); http://dx.doi.org/10.1116/1.571690 (1 page)

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Deep‐level defects play an important role in determining minority carrier lifetimes and noise in Hg1−xCdxTe devices.
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07.30.Cy Vacuum pumps
07.07.Tw Servo and control equipment; robots

The flash evaporation of low melting point materials

Frank Jansen

J. Vac. Sci. Technol. 21, 106 (1982); http://dx.doi.org/10.1116/1.571691 (2 pages)

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A new method for the congruent evaporation of fractionating materials with a low melting point is described. The technique allows positive control over the deposition rate while the apparatus does not involve any mechanically moving parts.
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81.20.-n Methods of materials synthesis and materials processing

Measurement and analysis of the phase diagram and thermodynamic properties in the Hg–Cd–Te system

Tse Tung, Ching‐Hua Su, Pok‐Kai Liao, and R. F. Brebrick

J. Vac. Sci. Technol. 21, 117 (1982); http://dx.doi.org/10.1116/1.571692 (8 pages) | Cited 23 times

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The liquidus surface of Hg1−xCdxTe(s) solid solutions, the liquidus lines in the Hg–Te and Cd–Te binaries, the pseudobinary liquidus and solidus, and the extensive partial pressure data are fit simultaneously. The liquid model assumed is one of which the interactions of the Hg, Cd, Te, HgTe, and CdTe species are represented in the excess Gibbs energy of mixing as a sum of quadratic and cubic terms in the species mole fractions with linarly temperature dependent coefficients. The overall fit is quantitatively satisfactory.
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64.70.D- Solid-liquid transitions
68.35.Md Surface thermodynamics, surface energies

Precipitation and phase stability of (Hg,Cd)Te

P. L. Anderson, H. F. Schaake, and J. H. Tregilgas

J. Vac. Sci. Technol. 21, 125 (1982); http://dx.doi.org/10.1116/1.571693 (4 pages) | Cited 7 times

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Precipitation of tellurium in solid (Hg,Cd)Te has been investigated. Review of phase equilibria data and review of conditions required for solid‐state precipitation demonstrates that the conditions necessary for precipitation exist along the tellurium‐saturated phase limit for (Hg,Cd)Te. Metallographic techniques have been used to demonstrate the existence of precipitate particles up to a density of 1012 cm−3 in solid‐state recrystallized (Hg,Cd)Te. The effects of such particles on the properties of (Hg,Cd)Te are discussed. It is shown that remnants of the Te precipitate structure would be expected to persist in post‐annealed (Hg,Cd)Te.
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64.75.-g Phase equilibria
81.30.-t Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
81.30.Mh Solid-phase precipitation

Theoretical calculation of Hg–Cd–Te liquidus–solidus phase diagram

R. Kikuchi

J. Vac. Sci. Technol. 21, 129 (1982); http://dx.doi.org/10.1116/1.571694 (4 pages) | Cited 6 times

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The liquidus‐solidus phase diagram of Hg‐Cd‐Te is calculated using the pair approximation of the cluster variation method. The work is an exten sion of previous III‐V work and includes association as an additional feature. The liquid phase is approximated by a pseodolattice structure and includes molecular species as well as atomic species. Vacancies are also considered in order to take the pressure effect into account. Unlike the regular solution model, the pair method can take into account the short‐range order in the liquid phase. Adjustable parameters (mostly energies) are first determined to fit Hg‐Te and Cd‐Te binary experiments. The association model can explain the assymetry and the sharp peak at 50% composition. These parameters and several additional ones constitute the one set of parameters (independent of temperature and composition) which are used to calculate the entire ternary liquidus‐solidus diagram Each parameter controls certain features of the diagram. Although the work is stil in progress, reasonably good agreement with known experi ments has ben achieved for both the Hg corner and the Te corner. The chemical potential diagram is discussed.
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64.70.D- Solid-liquid transitions
81.30.Bx Phase diagrams of metals, alloys, and oxides

The coherent potential approximation in disordered semiconducting alloys

H. Ehrenreich and K. C. Hass

J. Vac. Sci. Technol. 21, 133 (1982); http://dx.doi.org/10.1116/1.571695 (5 pages) | Cited 4 times

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The success of the coherent potential approximation (CPA) in obtaining semiquantitative theoretical descriptions of the electronic structure and the transport, optical, and magnetic properties of disordered metallic alloys has been recognized for some time. A more limited number of applications has been made to group IV and III–V alloys. This article reviews some of the aspects of the CPA relevant to the semiconductor problem. The theory is illustrated by new results for the complex band structure of disordered (Hg1−xCdx)Te, obtained by use of an empirical tight‐binding scheme and the parameters of Czyżyk and Podgórny for HgTe and CdTe.
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71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
71.15.-m Methods of electronic structure calculations

CPA band calculation for (Hg, Cd) Te

An‐Ban Chen and Arden Sher

J. Vac. Sci. Technol. 21, 138 (1982); http://dx.doi.org/10.1116/1.571696 (4 pages) | Cited 7 times

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A calculation of the electronic structure of (Hg,Cd)Te alloys in the coherent‐potential approximation (CPA) is presented. The problem is divided into three tasks: determining accurate band structures including relativistic terms for the constituent compounds (HgTe and CdTe), characterizing the alloy disorder, and executing the alloy calculation. These tasks are facilitated through the use of a set of symmetrized, orthonormal, local orbitals. We shall introduce the calculational procedure and discuss the results obtained to date. These include the calculated band structures for HgTe and CdTe, the local alloy disorder parameters, the alloy band energies, and density of states calculated in the virtual crystal approximation and in a simplified version of CPA.
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71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
71.15.-m Methods of electronic structure calculations

UPS study of the electronic structure of Hg1−xCdx Te: Breakdown of the virtual crystal approximation

J. A. Silberman, P. Morgen, I. Lindau, W. E. Spicer, and J. A. Wilson

J. Vac. Sci. Technol. 21, 142 (1982); http://dx.doi.org/10.1116/1.571697 (4 pages) | Cited 3 times

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Ultraviolet photoemission spectroscopy (UPS) with photon energies between 7 and 30 eV has been used to probe the electronic structure of cleaved (110) single‐crystal Hg1−xCdxTe (x = 0.2, 0.31, 0.39, and 1.0). Structure in the emission from the upper valence bands (within ∠3.5 eV of the valence band maximum) is qualitatively similar for the compositions studied and exhibits band‐structure‐related dispersion with photon energy. Features arising from the lower lying, mainly metal s‐electron derived states (−4 to −6 eV) correlate separately with Hg and Cd. Thus the UPS spectra give evidence of differences in the contributions of the two cations to the electronic structure and the breakdown of the virtual crystal approximation in the valence states lying about 5 eV below the valence band maximum.
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71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
81.65.-b Surface treatments

Localized orbital description of the electronic structure of Hg(1−x)Cdx Te pseudobinary alloys

Ronald D. Graft

J. Vac. Sci. Technol. 21, 146 (1982); http://dx.doi.org/10.1116/1.571698 (3 pages) | Cited 1 time

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The method of Kane and Chadi is applied to semiconducting Hg(1−x)Cdx Te alloys in the virtual crystal approximation. An atomic‐like basis set and an empirical pseudo potential Hamiltonian is solved exactly to all orders of interaction and orbital overlap. Gaussian orbital basis sets consisting of 5, 10, and 11 orbitals per atom are used to obtain an accurate description of the valence bands and the lowest three conduction bands. It is shown that a simple s,p basis set accurately describes the valence bands but is in error by several volts for lower lying conduction bands. Inclusion of d and f orbitals reduces the maximum valence band error by over 50%; the maximum error in the lower three conduction bands is reduced to 0.7 eV relative to an exact plane wave expansion using 80 waves. Spin‐orbit coupling is included by the method of Weisz as modified by Bloom and Bergstresser; calculated spin‐orbit splitting factors at Γ, X, and L are in good agreement with exact plane wave calculations.
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71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds

Surface and interfaces of HgCdTe. What can we learn from 3–5’s? What is unique with HgCdTe?

W. E. Spicer, J. A. Silberman, P. Morgen, I. Lindau, and J. A. Wilson

J. Vac. Sci. Technol. 21, 149 (1982); http://dx.doi.org/10.1116/1.571699 (5 pages) | Cited 4 times

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Fundamental studies of the wide variety of the surfaces and interfaces of mercury cadmium telluride are really only in their infancy. Major developments have been made in the understanding of the free surfaces of closely related 3–5 compound semiconductors and, making use of this knowledge, on the mechanism of formation of Schottky barriers and MOS (or MIS) interface states on the 3–5 materials. Thus, the 3–5 work provides an important starting point for HgCdTe work. For 3–5’s, a unified defect model has been developed which explains both the Schottky barrier formation and the source of the MOS interface states. This work is briefly reviewed and related to HgCdTe surface and interface phenomena. Based on this and a wide range of practical work plus the early results of fundamental work on HgCdTe, it is clear that defects also play an important role at HgCdTe interfaces. Previously however, it has apeared that the interface may not be so strongly coupled to defects in the bulk (i.e., to defects, dislocations, etc. in the bulk); this does not appear to be the case for HgCdTe where the ’’intercommunication’’ between the surface and bulk makes it essential to treat the surface in the context of bulk interactions and imperfections.
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73.20.-r Electron states at surfaces and interfaces
73.20.Hb Impurity and defect levels; energy states of adsorbed species
73.30.+y Surface double layers, Schottky barriers, and work functions
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions

Room temperature stability of cleaved Hg1−xCdxTe

J. A. Silberman, P. Morgen, I. Lindau, W. E. Spicer, and J. A. Wilson

J. Vac. Sci. Technol. 21, 154 (1982); http://dx.doi.org/10.1116/1.571701 (3 pages) | Cited 9 times

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X‐ray and ultraviolet photoemission spectroscopy (XPS and UPS) at 21.2 eV have been used to determine the stability against Hg evaporation of cleaved (110) surfaces of p‐Hg1−xCdxTe (x = 0.2, 0.31, 0.39) in vacuum at room temperature. No evidence of Hg loss was obtained for periods of observation from five to twenty hours. However, oxygen excited by an ionization gauge and Ne ion sputtering both produced preferential loss of Hg.
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68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
81.65.-b Surface treatments
81.40.Gh Other heat and thermomechanical treatments

Electrolyte electroreflectance study of the effects of anodization and of chemomechanical polish on Hg1−xCdxTe

A. Lastras‐Martinez, U. Lee, J. Zehnder, and P. M. Raccah

J. Vac. Sci. Technol. 21, 157 (1982); http://dx.doi.org/10.1116/1.571702 (4 pages) | Cited 10 times

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We havw shown that electrolyte electroreflectance (EER) can be used as a sensitive probe to study the effects of processing agents on the near surface bulk. Our results indicate that Br2/methanol may be damaging Hg‐annealed materials to a depth of about 600 Angstroms, depleting them in Cd and leaving their surfaces covered with a Te‐rich layer. While it is possible to remove the damaged layer anodization‐dissolution steps, our results show that such a procedure must be terminated when the undamaged material has been reached. If it is continued, the difference between the rates at which the Cd and Hg diffuse through the oxide would again deplete the interface in Cd.
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81.65.-b Surface treatments

AES sputter profiles of anodic oxide films on (Hg,Cd)Te

P. Morgen, J. A. Silberman, I. Lindau, W. E. Spicer, and J. A. Wilson

J. Vac. Sci. Technol. 21, 161 (1982); http://dx.doi.org/10.1116/1.571703 (3 pages) | Cited 7 times

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Sputter profiling with Auger electron spectroscopy has been used to determine the depth profiles of Hg,Cd,Te, and O in anodic oxides on (Hg,Cd)Te in an effort to monitor the composition of the oxides and the properties of the oxide‐semiconductor interface. The measurements are straightforward, but the analysis and extraction of atomic concentration profiles are complicated due to nonstoichiometric erosion of the base material and possibly of the oxide. Conclusions from this and earlier investigations about the composition of the semiconductor past the interface are still dependent on a more basal understanding of the effects of low energy ion nombardment on (Hg,Cd)Te.
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68.60.-p Physical properties of thin films, nonelectronic
79.20.Fv Electron impact: Auger emission
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Optical and field effect studies of the Hg0.7Cd0.3 Te–anodic oxide interface

R. B. Schoolar, B. K. Janousek, R. L. Alt, R. C. Carscallen, M. J. Daughtery, and A. A. Fote

J. Vac. Sci. Technol. 21, 164 (1982); http://dx.doi.org/10.1116/1.571704 (4 pages) | Cited 10 times

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This paper reports the effects of visible light and applied electric field on the properties of the HgCdTe–anodic oxide interface. The surfaces of anodized n‐type crystals are accumulated with a fixed positive charge in the oxide on the order of 5×1011 cm−2. However, illumination with photons of energy ?2.2 eV can neutralize and even invert these surfaces. The original surface charge is restored by placing the sample in the dark for periods of minutes at room temperature and weeks at 77 K. Based on our measurement of the oxide energy gap of 3.4 eV, the photo‐induced surface charging is attributed to internal photoemission of electrons from the HgCdTe valence band to the oxide conduction band. These photoemitted electrons fall into deep traps in the oxide and neutralize the fixed positive charge. When stored in the dark, these trapped electrons are thermally excited from the traps and recombined in the semiconductor. Charge exchange between the oxide traps and semiconductor can also be promoted by applying an electric field across the interface. Charge exchange occurs via tunneling, and the rate of charge exchange increases strongly with temperature, indicating that the trapped charge is distributed in energy. This effect saturates as the excess charge in the oxide neutralizes the applied field. Thus, under constant applied field, the original band bending in the semiconductor is eventually restored. From the temperature and time dependences of the trapping, the oxide traps are likely distributed both in energy and in distance from the semiconductor.
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81.65.-b Surface treatments
79.70.+q Field emission, ionization, evaporation, and desorption
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
73.30.+y Surface double layers, Schottky barriers, and work functions

Composition of native oxides and etched surfaces on Hg1−xCdxTe

D. R. Rhiger and R. E. Kvaas

J. Vac. Sci. Technol. 21, 168 (1982); http://dx.doi.org/10.1116/1.571705 (4 pages) | Cited 31 times

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Hg1−xCdxTe surfaces have been investigated by XPS and ellipsometry after spray etching or polish etching with Br solutions, and after the growth of native oxide films. Etching depletes the surface Cd, and enriches either Hg or Te depending on the etch method. Air‐grown native oxides after etching range up to 25 Å in thickness and are essentially TeO2. This thickness increases with increasing surface Te concentration, which depends on the etch. Native oxides 700 Å thick were grown by anodizing. Results are consistent with CdTeO3 as the major constituent. Stripping anodic oxides with HCl reveals a ∠100‐Å Te‐rich layer between the anodic oxide and substrate. A new way of comparing Hg1−xCdxTe native oxide films, the TeO2 stoichiometry plot, is introduced.
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81.05.Bx Metals, semimetals, and alloys
68.35.-p Solid surfaces and solid-solid interfaces: structure and energetics
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
79.60.Bm Clean metal, semiconductor, and insulator surfaces

The MIS physics of the native oxide–Hg1−xCdxTe interface

J. D. Beck, M. A. Kinch, E. J. Esposito, and R. A. Chapman

J. Vac. Sci. Technol. 21, 172 (1982); http://dx.doi.org/10.1116/1.571706 (6 pages) | Cited 11 times

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Several key aspects of HgCdTe metal–insulator–semiconductor (MIS) device physics affecting the interpretation and analysis of admittance‐voltage data are discussed. The effect of degenerate statistics on the capacitance–voltage (C–V) characteristics of n‐type devices biased into accumulation and p‐type devices biased into inversion is demonstrated experimentally on MIS test devices with native oxide interfaces. Theoretical calculations using degenerate statistics and the k⋅p approximation are shown to predict the observed C–V behavior. Tunneling via Shockley–Read levels as it affects thermal equilibrium measurements of admittance‐voltage data is compared for the cases of p‐type and n‐type devices. Inversion layer quantization effects are observed in p‐type device tunneling phenomena, while n‐type devices exhibit tunneling behavior which is very sensitive to band‐gap states near the surface. Oscillations in conductance–voltage (G–V) data on p‐type devices are attributed to inversion layer quantization effects while the droop in low‐frequency G–V data on anodic oxide interface devices on n‐type material is attributed to a high density of subsurface band‐gap states introduced during the anodic oxide growth process. Multiple flatband effects in anodic oxide MIS devices with opaque and transparent gate regions can be induced by visible light exposure which creates a lateral nonuniformity in fixed charge at the oxide–HgCdTe interface.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

The growth of CdxHg1−xTe using organometallics

J. B. Mullin and S. J. C. Irvine

J. Vac. Sci. Technol. 21, 178 (1982); http://dx.doi.org/10.1116/1.571707 (4 pages) | Cited 15 times

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The growth of layers of cadmium mercury telluride (CMT) by metal organic vapor phase epitaxy is discussed with special reference to the underlying factors that determine composition. It has been shown in an experimental study that whereas the value of the composition parameter x is substantially constant from ∠410 °C to at least ∠435 °C the value of x progressively increases to unity with a decrease in temperature below ∠410 °C. The cause of this phenomenon has been identified with the mechanism of pyrolysis of the alkyls.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.-a Thin film structure and morphology

Growth of HgCdTe films by laser induced evaporation and deposition

J. T. Cheung and D. T. Cheung

J. Vac. Sci. Technol. 21, 182 (1982); http://dx.doi.org/10.1116/1.571708 (5 pages) | Cited 14 times

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Hg1−xCdxTe, the evaporation is congruent. Films were deposited at different substrate temperatures in a Hg partial pressure. The as‐deposited films were stoichiometric and exhibit a strong 〈111〉 texture. As‐grown films are n‐type with electron mobility as high as 2×104 cm2/V‐s at 77 K.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Effects of deep‐level defects in Hg1−xCdxTe provided by DLTS

C. E. Jones, V. Nair, J. Lindquist, and D. L. Polla

J. Vac. Sci. Technol. 21, 187 (1982); http://dx.doi.org/10.1116/1.571709 (4 pages) | Cited 17 times

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Deep‐level defects play an important role in determining minority carrier lifetimes and noise in Hg1−xCdxTe devices. Previous work on deep‐level defects in Hg1−xCdxTe has been meager because there have not been good experimental methods available to observe or characterize them. Deep‐level transient spectroscopy has now begun to provide information on concentrations, energy levels, and capture cross sections for defects in Hg1−xCdxTe. This paper reviews the DLTS results to date on nonstoichiometric (Hg lean) and copper‐doped material. In both cases, trends are beginning to appear for the trap levels as a function of x. Nonstoichiometric material commonly shows generation‐recombination centers at Ev+0.4 Egap and Ev+0.75 Egap. Copper‐doped material commonly shows two levels pinned to the valence band at about Ev+0.06 eV and Ev+0.15 eV. The capture cross sections and concentrations measured by DLTS have been used to calculate the effect these centers have on minority carrier lifetime and noise (R0A). In most cases the measured values are within experimental error of those calculated from DLTS data. The deep‐generation recombination centers characterized thus far seem to be very important in controlling minority carrier lifetime, noise currents, and R0A.
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78.30.Er Solid metals and alloys
78.40.Kc Metals, semimetals, and alloys
61.72.U- Doping and impurity implantation
71.20.-b Electron density of states and band structure of crystalline solids

A DLTS study of deep levels in n‐type CdTe

R. T. Collins, T. F. Kuech, and T. C. McGill

J. Vac. Sci. Technol. 21, 191 (1982); http://dx.doi.org/10.1116/1.571710 (4 pages) | Cited 9 times

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We report the results of a DLTS study on the majority carrier deep level structure of three samples of n‐type CdTe and the effects on the deep level structure of indium doped CdTe due to H2 annealing. H2 annealing did not qualitatively change the deep level structure of the annealed sample. It did cause the shallow level concentration to decrease with a proportional decrease in the deep level concentrations as a result of indium out‐diffusion and compensation by native defects. Levels present in all of the materials studied have been characterized and attributed to either native defects or innate chemical impurities. Other levels present in indium doped material require above band gap illumination of the sample before they are observed. A possible model proposes that these levels arise from defect complexes.
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71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
71.55.Ht Other nonmetals
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization

Pseudopotential theory of the alloy broadening of defect levels

S. Wu, C.‐L. Wang, and D.‐S. Pan

J. Vac. Sci. Technol. 21, 195 (1982); http://dx.doi.org/10.1116/1.571711 (3 pages) | Cited 1 time

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We have studied the effect of the alloy fluctuation potential in Hg1−xCdxTe on the shallow acceptor and donor states by an empirical pseudopotential model. The root mean squares of the broadenings are calculated by a simple perturbation theory for x from 0.2 to 1.0. We found that the shallow acceptors are broadened by about 5 meV with the maximum broadening occurring at x = 0.6 and the shallow donors are broadened by a maximum amount of 1 meV at x = 0.8. Estimates of the broadening of deep levels indicate an upper bound of 0.1 eV.
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78.30.Er Solid metals and alloys
78.40.Kc Metals, semimetals, and alloys
71.35.-y Excitons and related phenomena
71.20.Mq Elemental semiconductors
71.70.-d Level splitting and interactions

Bulk vacancies in CdxHg1−xTe

C. A. Swarts, M. S. Daw, and T. C. McGill

J. Vac. Sci. Technol. 21, 198 (1982); http://dx.doi.org/10.1116/1.571712 (3 pages) | Cited 4 times

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We report the first theoretical study of vacancies in CdxHg1−xTe alloys. The study employs the tight‐binding method for obtaining the Hamiltonian. The Slater–Koster Green’s function method is used to obtain the electronic states that result from removing a cation or anion from the virtual crystal used to model the alloys. The primary results are that the anion vacancy levels are far into the conduction band and hence are not likely to produce levels in the gap. In contrast, the cation vacancy is found to produce levels near the valence band edge. We find that spatially these states are very localized on the atoms nearest the vacancy.
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61.72.jd Vacancies
61.72.jj Interstitials
71.20.Nr Semiconductor compounds
71.20.Ps Other inorganic compounds
78.30.Er Solid metals and alloys
78.40.Kc Metals, semimetals, and alloys

Conductivity type conversion in (Hg,Cd)Te

A. J. Syllaios and M. J. Williams

J. Vac. Sci. Technol. 21, 201 (1982); http://dx.doi.org/10.1116/1.571715 (4 pages) | Cited 2 times

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The behavior of native defects in Hg0.70Cd0.30Te and Hg0.77Cd0.23Te prepared by solid state recrystallization has been investigated. Galvanomagnetic data on n‐type samples reannealed under various conditions in Hg vapor are presented. Reconversion from n‐type to p‐type conductivity is found to depend on sample composition and temperature, ambient Hg pressure, and on the residual extrinsic donor impurity concentration. It is concluded that conductivity‐type conversion in (Hg,Cd)Te may be mainly attributed to residual extrinsic donor impurities and dominant native acceptor defects in agreement with previously published results.
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72.60.+g Mixed conductivity and conductivity transitions
72.20.My Galvanomagnetic and other magnetotransport effects
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
81.40.Rs Electrical and magnetic properties related to treatment conditions

Luminescence studies of HgCdTe alloys

A. T. Hunter and T. C. McGill

J. Vac. Sci. Technol. 21, 205 (1982); http://dx.doi.org/10.1116/1.571716 (3 pages) | Cited 16 times

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We report the observation in Hg1−xCdxTe of band‐to‐band, band‐to‐acceptor, and donor–acceptor luminescence for material of x = 0.32 and 0.5, and bound exciton recombination luminescence, for material of x = 0.5. The band‐to‐band lineshape and variation in intensity with pump power are appropriate to an electron‐hole plasma with recombination proceeding without wave vector conservation. Differences between the spectra among the four 0.5 samples studied are attributed to variations in the Hg vacancy concentration. Shifts in luminescence energy across one of the x = 0.32 samples imply a change in composition across the surface of the sample of 0.03 cm−1. The absence of bound exciton luminescence in the x = 0.32 samples is consistent with theoretical calculations by Osbourn and Smith showing a radiative efficiency of 20% for bound excitons in material of this composition and 90% for x = 0.48 material. From line shape separations, we estimate acceptor binding energies of 14.0±1.0 and 15.5±2.0 meV in x = 0.32 and 0.48 materials, respectively, and donor binding energies of 1.0±1.0 and 4.5±2.0 meV, respectively.
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78.55.Hx Other solid inorganic materials
71.35.-y Excitons and related phenomena
78.30.Er Solid metals and alloys
78.40.Kc Metals, semimetals, and alloys

EBIC characterization of recrystallized HgCdTe

J. H. Tregilgas

J. Vac. Sci. Technol. 21, 208 (1982); http://dx.doi.org/10.1116/1.571717 (4 pages) | Cited 4 times

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Electron beam induced current (EBIC) images of skin junctions formed during postannealing in excess Hg have been used to study recrystallized HgCdTe. The skin junction has been found to be nonplanar, and variations in its position are consistent with the dissolution of second‐phase Te. EBIC images have demonstrated enhance diffusion of Hg along grain boundaries, in addition to suggesting that these boundary regions can be electrically active as carrier generation centers. Dislocation subgrain boundaries, which have also been observed, appear to be active as recombination centers.
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81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
66.30.Lw Diffusion of other defects
61.72.Mm Grain and twin boundaries

Use of Rutherford backscattering and channeling in the study of (Hg,Cd)Te

K. L. Conway, J. F. Gibbons, and T. W. Sigmon

J. Vac. Sci. Technol. 21, 212 (1982); http://dx.doi.org/10.1116/1.571718 (3 pages) | Cited 3 times

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Backscattering and channeling of MeV 4He+ ions have been used to monitor the near surface region of both bulk and epitaxial (Hg,Cd)Te before and after thermal processing and implantation. At 2.8 MeV the Hg, Cd, and Te surface peaks are clearly visible in the channeled spectra. Redistribution of mercury is visible in random spectra following thermal processing. The shape of spectra from layered samples is explained qualitatively. For laser‐deposited HgCdTe on 〈111a〉 CdTe, annealing under a laser‐deposited CdTe cap up to 170 °C for 10 h produced no changes. However, redistribution of mercury was observed following anneals at 230 °C for 10 h and 250 °C for 11.75 h. Channeling effect measurements showed that no solid phase epitaxial growth had occurred for these samples. In HgCdTe samples implanted with 1014 11B+/cm−2 at 250 keV, buried damage was observed in the channeled spectra.
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66.30.Fq Self-diffusion in metals, semimetals, and alloys
61.85.+p Channeling phenomena (blocking, energy loss, etc.)
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces

Electronic properties of HgCdTe

M. A. Kinch

J. Vac. Sci. Technol. 21, 215 (1982); http://dx.doi.org/10.1116/1.571719 (5 pages) | Cited 16 times

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The electronic properties of HgCdTe relevant to the operation of photoconductive, photovoltaic, and metal–insulator–semiconductor (MIS) infrared devices will be reviewed. Particular consideration will be given to minority and majority carrier phenomena such as mobility, lifetime, and transition rates occurring in the bulk, surface, and depletion regions of HgCdTe devices.
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72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.80.Ey III-V and II-VI semiconductors
85.60.Gz Photodetectors (including infrared and CCD detectors)
85.30.Mn Junction breakdown and tunneling devices (including resonance tunneling devices)

Electrical, optical, and magnetic properties of Hg1−xMnxTe

J. K. Furdyna

J. Vac. Sci. Technol. 21, 220 (1982); http://dx.doi.org/10.1116/1.571720 (9 pages) | Cited 33 times

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We discuss the band structure and the optical, electrical, and magnetic properties of the compound semiconductor Hg1−xMnxTe, formed by substitution of the magnetic Mn ions for Hg in the HgTe lattice. In the absence of a magnetic field, this alloy is very similar to its sister compound Hg1−xCdxTe. Although Mn is not a group II element, Hg1−xMnxTe crystallizes in the zincblende structure, forming good quality crystals up to x≊0.35. Its energy gap and related band parameters vary with x, but at a rate about twice as fast as in Hg1−xCdxTe. The electrical properties of Hg1−xMnxTe are again similar to those of Hg1−xCdxTe, exhibiting, e.g., electron mobilities in excess of 106cm2/V⋅s. Because Mn is a magnetic ion, Hg1−xMnxTe differs from Hg1−xCdxTe in its magnetic properties, as well as in the behavior of its electrical and optical properties in the presence of a magnetic field. For example, for x≳0.17 Hg1−xMnxTe exhibits a transition to the spin glass phase at low temperatures. Furthermore, the presence of Mn ions leads to an exchange interaction between the localized magnetic moments and the band electrons, which in turn affects the band parameters and leads to new and spectacular effects in the transport and optical properties.
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72.80.Ey III-V and II-VI semiconductors
75.20.En Metals and alloys
75.30.Hx Magnetic impurity interactions
75.30.Cr Saturation moments and magnetic susceptibilities

Some properties of a high density electron‐hole plasma in Hg1−xCdxTe

A. V. Nurmikko and B. D. Schwartz

J. Vac. Sci. Technol. 21, 229 (1982); http://dx.doi.org/10.1116/1.571721 (2 pages) | Cited 1 time

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Picosecond infrared techniques have been used to probe the time‐varying transmission and reflection coefficients at 10.6 μm of a nonequilibrium electron‐hole gas in Hg1−xCdxTe (x = 0.3 and 0.2) at peak densities of approximately 1×1019 cm−3. Observed recombination times are much longer than those predicted by extrapolations based on conventional theory of Auger recombination in the nondegenerate density regime.
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71.35.-y Excitons and related phenomena
78.30.Hv Other nonmetallic inorganics

Plasmon‐assisted recombination in narrow‐gap semiconductors in a magnetic field

P. A. Wolff, C. Verie, and S. Y. Yuen

J. Vac. Sci. Technol. 21, 231 (1982); http://dx.doi.org/10.1116/1.571722 (6 pages)

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This paper presents calculations of the effect of large magnetic fields on the plasmon‐assisted recombination process in narrow‐gap semiconductors. Minority carriers, in materials such as n‐ (Pb,Sn)Te or n‐(Hg,Cd)Te, are believed to recombine via plasma wave emission when EG?h̸ωp. Lifetimes in the 10−12–10−13 s range are anticipated. This large recombination rate precludes stimulated plasma wave emission. Magnetic fields change the plasmon recombination process in two ways. Landau level quantization enhances the electron state density at the band edge, increasing the gain of k = 0 plasma modes. The field also modifies the plasmon dispersion relation. This effect can be exploited to inhibit recombination via plasma modes propagating across the field, and to increase the recombination time. The two effects combine to yield a threshold pumping level for stimulated plasma wave emission in the 10–100 kW/cm2 range.
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71.45.Gm Exchange, correlation, dielectric and magnetic response functions, plasmons
72.80.Ey III-V and II-VI semiconductors
72.80.Jc Other crystalline inorganic semiconductors

Theory for electron mobilities in n‐type Hg1−xCdxTe and CdTe at low temperatures

J. R. Meyer and F. J. Bartoli

J. Vac. Sci. Technol. 21, 237 (1982); http://dx.doi.org/10.1116/1.571723 (4 pages) | Cited 10 times

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Kohler’s variational method is employed to calculate electron mobilities for n‐type Hg1−xCdxTe and CdTe. Scattering mechanisms considered include ionized and neutral impurity scattering, acoustic, piezoelectric, and optical phonon scattering, and disorder scattering. Ionized impurity cross‐sections are derived from the partial wave phase shift method, since use of the Born approximation can lead to significant error. Because the absence of carrier freeze‐out prevents an independent determination of compensation densities for Hg1−xCdxTe , a direct comparison with experiment is possible only for CdTe. In that case the agreement is relatively good down to about 30 K, but the theoretical values of mobility are greater than the measured values at the lowest temperatures. Similar behavior has already been observed in other semiconductors, and is probably due at least in part to the effects of multi‐ion scattering. The application of the phase shift method to p‐type Hg1−xCdxTe is also briefly considered. Criteria for the validity of the Born approximation and the single‐site scattering model are discussed.
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72.10.Di Scattering by phonons, magnons, and other nonlocalized excitations
72.10.Fk Scattering by point defects, dislocations, surfaces, and other imperfections (including Kondo effect)
72.20.Dp General theory, scattering mechanisms
72.80.Ey III-V and II-VI semiconductors

Photo‐Hall measurements on laser‐generated electron‐hole plasmas in Hg1−xCdxTe

F. J. Bartoli, J. R. Meyer, R. E. Allen, and C. A. Hoffman

J. Vac. Sci. Technol. 21, 241 (1982); http://dx.doi.org/10.1116/1.571725 (3 pages) | Cited 5 times

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Photo‐Hall techniques have been employed to study mobilities in photoexcited n‐type Hg1−xCdxTe (x≊0.2) at low temperatures (T≊10 K). Excitation is provided by pulses of either 25 μs or 200 ns duration from a CO2 laser. At low excitation levels, acceptor neutralization causes the mobility to increase in a manner sensitive to the degree of compensation present in the sample. At higher excitation the mobility decreases monotonically due to electron‐hole scattering. Comparison is made to a transport theory for optically generated plasmas in semiconductors with nonparabolic bands. The calculation includes a partial‐wave phase shift treatment of ionized impurity and electron‐hole scattering, screening by the photoexcited carriers, and alloy scattering. At high excitation levels the mobility is found to depend strongly on the ’’dynamic’’ nature of the free carrier screening of electron‐hole interactions.
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72.40.+w Photoconduction and photovoltaic effects
72.80.Ey III-V and II-VI semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Electron mobility in LPE Hg1−xCdxTe/CdTe layers near zero band‐gap crossing

J. Bajaj, S. H. Shin, G. Bostrup, and D. T. Cheung

J. Vac. Sci. Technol. 21, 244 (1982); http://dx.doi.org/10.1116/1.571726 (3 pages) | Cited 3 times

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The electron mobility in n‐type Hg1−xCdxTe has been studied as a function of temperature in the vicinity of zero band‐gap crossing. The temperature range covered in these experiments was 5–300 K, and the samples studied were liquid phase epitaxial Hg1−xCdxTe/CdTe layers. A distinct narrow peak in the mobility μH is observed for x = 0.16 at 40 K, which we interpret as an effect related to zero band‐gap crossing. The value of μH at the peak is 1.3×106 cm2 V−1 s−1.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
72.20.My Galvanomagnetic and other magnetotransport effects
72.80.Ey III-V and II-VI semiconductors

Impurity‐to‐band tunneling in Hg1−xCdxTea)

H. J. Hoffman and W. W. Anderson

J. Vac. Sci. Technol. 21, 247 (1982); http://dx.doi.org/10.1116/1.571727 (4 pages) | Cited 2 times

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Theoretical modeling of deep level impurity‐to‐band tunneling is carried out in the framework of time‐dependent perturbation theory. The basic method is formulated by analogy with the hydrogen ionization problem in a uniform electric field. Based on the WKB approximation, an asymptotic expansion for the wave function in the space charge region is used to derive explicit expressions for the transition matrix element W, assuming a Coulomb potential for the localized center. Comparison with the only known experimental estimate (gold doped silicon for which ‖W‖2∠10−47 erg2 cm3) yields a reasonably close agreement with our theoretical value. Furthermore, the theoretical result is found to be markedly insensitive to the choice of the trap potential. Further improvements in the theory can be accomplished by taking band nonparabolicity into account and relaxing the constant field approximations. Application of the theory to find the generation–recombination rate for this process leads to a pronounced peak in the I‐V characteristic for a set of device parameters chosen to approximate the case of an InSb diode in which such a peak has been observed experimentally.
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73.40.Gk Tunneling
73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
78.40.Fy Semiconductors
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Behavior of implantation‐induced defects in HgCdTe

L. O. Bubulac, W. E. Tennant, R. A. Riedel, and T. J. Magee

J. Vac. Sci. Technol. 21, 251 (1982); http://dx.doi.org/10.1116/1.571728 (4 pages) | Cited 28 times

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The characteristics of ion implanted HgCdTe epitaxial layers have been explored. A bimodal distribution in damage near the implanted surface has been correlated with a bimodal distribution in implant‐induced donor concentration. The implant induced junction depth has been found to be controllable and stable under a range of annealing conditions. Differential capacitance measurements have shown that the carrier concentration in the junction region is 10–100 times lower than the as‐grown acceptor concentration in the base material. These and other observations have been qualitatively explained by a model based on the hypothesis that Hg interstitials (or possibly Te vacancies) formed during the implant are donors whose distribution is largely controlled by damage near the layer surface.
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73.40.Lq Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
61.72.U- Doping and impurity implantation
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients
61.72.jd Vacancies
61.72.jj Interstitials

Effects of implantation and annealing temperatures on implantation induced damage in HgCdTe

S. Y. Wu, W. J. Choyke, W. J. Takei, A. J. Noreika, M. H. Francombe, and R. B. Irwin

J. Vac. Sci. Technol. 21, 255 (1982); http://dx.doi.org/10.1116/1.571729 (4 pages) | Cited 5 times

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A preliminary investigation of the effects of implantation and annealing temperatures on implantation induced damage in HgCdTe was undertaken. Rutherford backscattering (RBS) channeling experiments were used to study the surface condition and distribution of implantation induced defects in the crystal. Secondary ion mass spectroscopy (SIMS) was used to determine the implanted boron profiles. The migration and depth distribution of defects under various thermal annealing conditions in HgCdTe implanted at room and liquid nitrogen temperatures are described.
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61.72.U- Doping and impurity implantation
81.40.Ef Cold working, work hardening; annealing, post-deformation annealing, quenching, tempering recovery, and crystallization
61.80.Jh Ion radiation effects
61.72.sd Impurity concentration
61.72.sh Impurity distribution
61.72.sm Impurity gradients

Effect of diffusion and drift on generation–recombination in HgCdTe photoconductors

D. L. Smith, S. K. Lo, and J. D. Genova

J. Vac. Sci. Technol. 21, 259 (1982); http://dx.doi.org/10.1116/1.571730 (4 pages) | Cited 7 times

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We present calculations and measurements of the bias field dependence of generation– recombination (g–r) noise and D∗ in x∠0.2 HgCdTe photoconductors. The field dependence of the noise and D∗ depend on whether the detector noise is background or thermal dominated. For the background dominated case, the noise voltage increases linearly with field at low field and saturates at high field. D∗ initially increases with bias field and saturates at high field. For the thermal dominated case, the noise voltage initially increases linearly with bias field at low field and continues to increase like the square root of the field at large fields. D∗ decreases with increasing field in the thermal dominated case. Comparison is made between the theoretical and experimental results and good agreement is found.
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85.30.Tv Field effect devices
85.60.Gz Photodetectors (including infrared and CCD detectors)
29.40.Wk Solid-state detectors
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