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Nov 1969

Volume 6, Issue 6, pp. 929-969


S-Type Current–Voltage Characteristics in Some Film Systems and their Interpretation

A. G. Zhdan, V. B. Sandomyrskii, M. I. Elinson, and M. E. Tchugunova

J. Vac. Sci. Technol. 6, 929 (1969); http://dx.doi.org/10.1116/1.1492727 (5 pages)

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Advances in investigations of switching phenomena in glassy semiconductors give a possibility of a new interpretation of results on the study of anomalous field emission (AFE) that we observed earlier in thin (<1 μ layers of an amorphous quartz doped with carbon. The main AFE characteristics are quite similar to switching characteristics in glasses, namely, AFE current-voltage characteristics are of the S-type and these characteristics have a high velocity of transition from a high ohmic state to low ohmic state. The AFE phenomenon is quite reproducible. On the emission pictures of AFE in the Muller microscope we observed a distinct narrow current channel which is typical of S-type characteristics. The current densities of AFE were ≃104 A∕cm2, and the emission was stable in relatively low vacuum (≃10−7 Torr). The velocity spectrum of electrons in the AFE process is considerably wider than in the normal field emission process. Thus the AFE method is quite an effective tool for investigations of physical mechanisms of switching in similar systems. We have also investigated switching phenomena in CdS single crystal films on Ge. In this system we also observed S-type characteristics having parameters which were dependent on the Ge volume properties and on the conditions of CdS deposition. The theory of switching mechanism for the systems containing a high trap concentration is developed. This theory is based on the idea of space charged limited currents and on the effect of disappearance of local level during screening by free carriers. The theory describes qualitatively many features of switching phenomena in glassy semiconductors.
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79.70.+q Field emission, ionization, evaporation, and desorption
73.50.Gr Charge carriers: generation, recombination, lifetime, trapping, mean free paths
77.55.-g Dielectric thin films

Preparation of Oxide Films by Pyrolysis and Investigation of their Structure Sensitive Properties

L. A. Ryabova and Ya. S. Savitskaya

J. Vac. Sci. Technol. 6, 934 (1969); http://dx.doi.org/10.1116/1.1492728 (4 pages) | Cited 5 times

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Some experimental data are given on the preparation of insulating oxide films (ZnO, In2O3, Al2O3) by the pyrolysis of approximate metal-organic compounds. It is shown that these oxide films may be prepared by the pyrolysis method with a large range of structures varying from amorphous to single crystal and with different electrophysical properties. Temperature ranges for growth of amorphous and crystalline phases were established. Using the amorphous In2O3 and Al2O3 films metal–In2O3–metal and metal–Al2O3–metal samples were prepared. These devices have two stable electrical states, namely, they may be either in a conductive or a nonconductive state. The influence of heat treatment upon the structure and resistivity of the films was studied. The In2O3 films am most sensitive to heat treatment, i.e., the amorphous films became crystalline, and in the process their resistivities decreased five orders.
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81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.-a Thin film structure and morphology
73.61.Ng Insulators
68.60.Dv Thermal stability; thermal effects

Some Physical Properties of Si–Si3N4 Interfaces and Silicon Nitride Thin Films Prepared by Reactive Sputtering in Nitrogen

J. C̆ervenák, L. N. Aleksandrov, R. N. Lovjagin, and E. A. Krivorotov

J. Vac. Sci. Technol. 6, 938 (1969); http://dx.doi.org/10.1116/1.1492729 (3 pages) | Cited 1 time

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In this work the influence of the surface layers (amorphous, polycrystalline) on single-crystalline Si substrates upon the form and frequency dependence of the C-U characteristics is experimentally investigated. Measurements have been made with Al–Si3N4–Si structures in which Si3N4, thin layers have been prepared by reactive cathodic sputtering in nitrogen. The breakdown voltage of Si3N4 layers has been found in the region (2–7)×106 V∕cm, with a dielectric constant of 6–7 and a refraction index of 2.
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73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
77.55.-g Dielectric thin films
77.22.Jp Dielectric breakdown and space-charge effects
78.66.Nk Insulators

Cryosorption Pumping of Air on Molecular Sieves at 77 K—The Ultimate Achievable Vacuum

S. A. Stern and F. S. DiPaolo

J. Vac. Sci. Technol. 6, 941 (1969); http://dx.doi.org/10.1116/1.1492730 (10 pages) | Cited 1 time

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The cryosorption pumping of air and some of its components on Molecular Sieve 5A pellets was studied at 77 K and in the pressure range from atmospheric to about 10−6 Torr. The lowest residual pressures attainable in an enclosure by cryosorption pumping of air was calculated by the graphical method of Turner and Feinleib, using the latest adsorption isotherm data available. This method was also used to evaluate the relative efficiency of single-stage and two-stage cryosorption pumping. In the latter case, it is shown that much lower residual pressures can be reached by isolation of the “non-condensable” air components in the first pumping stage under dynamic conditions than by allowing this stage to reach adsorption equilibrium. The calculations were confirmed experimentally by means of a new type of cryosorption pump. This pump was designed to optimize heat transfer between adsorbent pellets and refrigerant fluid, as well as gas flow at transition range pressures.
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07.30.Cy Vacuum pumps
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Use of a Cooled Quartz Crystal Microbalance to Study the Molecular Flow and Condensation of CO2 in Vacuum

M. A. Baker and L. Holland

J. Vac. Sci. Technol. 6, 951 (1969); http://dx.doi.org/10.1116/1.1492731 (4 pages)

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The molecular condensation rate and condensation characteristics of a collimated molecular beam of carbon dioxide were determined using a h.f. crystal microbalance. The CO2 molecules were condensed on a quartz vibrator cooled with liquid nitrogen. An analysis was made of the contributions to the total condensation rate of the preferred and randomized gas flows using different crystal positions and orientations. Molecular intensity distribution of the CO2 beam was measured with the quartz vibrator mounted on a probe which traversed the beam. The effect of different angles of beam incidence on the condensation rate was studied by rotating the quartz vibrator in a uniform part of the beam. The results showed deviations from the cosine law after initial condensation at non-normal incidence. The condensation followed the cosine law for thick deposits and this was attributed to incident molecules making several collisions in a porous layer.
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47.45.Dt Free molecular flows
68.03.Fg Evaporation and condensation of liquids
68.43.Mn Adsorption kinetics
37.20.+j Atomic and molecular beam sources and techniques

A Novel Sweep Method for Monopole Mass Spectrometers

Richard F. Herzog

J. Vac. Sci. Technol. 6, 955 (1969); http://dx.doi.org/10.1116/1.1492732 (3 pages)

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The regular mass range of the monopole mass spectrometer can be extended to very high mass numbers if at the end of the regular mass range, the maximum ac rod voltage is kept constant and the dc rod voltage is reduced. During this extended mass range the mass is inversely proportional go this dc voltage. If the ion energy is kept constant the sensitivity stays essentially constant over the whole mass range and the resolution is inversely proportional to the mass. If the ion energy is reduced in proportion to the dc voltage the resolution stays constant, but the sensitivity is reduced. This method of mass scan permits with excellent sensitivity the detection of vacuum system contaminants of very high molecular weight. The total scanning time necessary to cover this wide mass range is much shorter than the time required for a regular scan over the same mass range.
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07.75.+h Mass spectrometers

Practical Application of Leak Detection Methods

H. F. McKinney

J. Vac. Sci. Technol. 6, 958 (1969); http://dx.doi.org/10.1116/1.1492733 (7 pages)

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The 12 major leak detection methods that are commonly used are analyzed and discussed in this paper. Problem areas that are encountered when using these leak detection methods are also discussed. A brief discussion of the four main categories of system leakages is presented. Details of several representative leak detection programs are also presented and include both quantitative and qualitative analyses. Experimental experience is generalized in this paper in order to develop standardized application of various leak detection methods.
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07.30.Hd Vacuum testing methods; leak detectors

Insulating Rotary and Translational Ultrahigh Vacuum Seal

Richard A. Carey

J. Vac. Sci. Technol. 6, 965 (1969); http://dx.doi.org/10.1116/1.1492734 (1 page) | Cited 5 times

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Abstract Unavailable
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Cryosorption Pumping of Helium on Porous Silver at 4.2 K

J. P. Hobson and B. R. Williams

J. Vac. Sci. Technol. 6, 965 (1969); http://dx.doi.org/10.1116/1.1492735 (3 pages)

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Abstract Unavailable
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07.30.Cy Vacuum pumps
07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment

Getter-Ion Pump Employing Penning Discharges

John C. Helmer

J. Vac. Sci. Technol. 6, 967 (1969); http://dx.doi.org/10.1116/1.1492736 (2 pages)

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Abstract Unavailable
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07.30.Cy Vacuum pumps
52.80.Sm Magnetoactive discharges (e.g., Penning discharges)

A “Two-Bit” Variable Leak Valve

H. Helbig, D. Millis, and L. Todd

J. Vac. Sci. Technol. 6, 968 (1969); http://dx.doi.org/10.1116/1.1492737 (1 page)

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Abstract Unavailable
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07.30.Kf Vacuum chambers, auxiliary apparatus, and materials

Purging Probe Aids Vacuum-Leak Detection

K. B. Wear

J. Vac. Sci. Technol. 6, 968 (1969); http://dx.doi.org/10.1116/1.1492738 (2 pages)

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Abstract Unavailable
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07.30.Hd Vacuum testing methods; leak detectors

Errata: In Situ Transmission Electronmicroscopic Study of Crystal Growth by Chemical Vapor Deposition

T. Gabor and J. M. Blocher

J. Vac. Sci. Technol. 6, 969 (1969); http://dx.doi.org/10.1116/1.1492739 (1 page)

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Abstract Unavailable
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
68.37.Lp Transmission electron microscopy (TEM)
99.10.Cd Errata
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