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Sep 2013

Volume 31, Issue 5 (partial)

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Review of radiation damage in GaN-based materials and devices

Stephen J. Pearton, Richard Deist, Fan Ren, Lu Liu, Alexander Y. Polyakov, and Jihyun Kim

J. Vac. Sci. Technol. A 31, 050801 (2013); http://dx.doi.org/10.1116/1.4799504 (16 pages)

Online Publication Date: 9 April 2013

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A review of the effects of proton, neutron, γ-ray, and electron irradiation on GaN materials and devices is presented. Neutron irradiation tends to create disordered regions in the GaN, while the damage from the other forms of radiation is more typically point defects. In all cases, the damaged region contains carrier traps that reduce the mobility and conductivity of the GaN and at high enough doses, a significant degradation of device performance. GaN is several orders of magnitude more resistant to radiation damage than GaAs of similar doping concentrations. In terms of heterostructures, preliminary data suggests that the radiation hardness decreases in the order AlN/GaN > AlGaN/GaN > InAlN/GaN, consistent with the average bond strengths in the Al-based materials.
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61.80.Jh Ion radiation effects
81.05.Ea III-V semiconductors
61.80.Hg Neutron radiation effects
61.80.Ed γ-ray effects
61.72.J- Point defects and defect clusters
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping

Atomically resolved force microscopy

Seizo Morita

J. Vac. Sci. Technol. A 31, 050802 (2013); http://dx.doi.org/10.1116/1.4803094 (18 pages)

Online Publication Date: 1 May 2013

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Atomic force microscopy (AFM) with atomic resolution has opened up a new “atom world” based on the chemical nanoscale force. In the noncontact regime where a weak attractive chemical force appears, AFM has successfully achieved atomically resolved imaging of various surfaces. In the near-contact regime, where a strong attractive chemical force or Pauli repulsive force appears, AFM can map the force and potential even on insulator surfaces, it can identify the chemical species of individual atoms using the chemical force, manipulate embedded heterogeneous atoms vertically and laterally, image individual chemical bonds using the Pauli repulsive force, and detect the energy gap opening induced by covalent bond formation in combination with scanning tunneling microscopy.
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68.37.Ps Atomic force microscopy (AFM)
61.50.Lt Crystal binding; cohesive energy
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)

Nanostructured materials for supercapacitors

M. Meyyappan

J. Vac. Sci. Technol. A 31, 050803 (2013); http://dx.doi.org/10.1116/1.4802772 (14 pages)

Online Publication Date: 9 May 2013

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Supercapacitor is an energy storage device that attempts to combine the high power density of a capacitor with the high energy density of a battery. Conventional supercapacitors use carbon based electrodes, mostly graphite. In recent years, alternatives such as carbon nanotubes, graphene, and other nanostructured materials have been considered to construct supercapacitor electrodes. This article reviews the progress in this area in addition to presenting a brief background on supercapacitors as energy storage medium and nanomaterials.
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88.80.fh Supercapacitors
82.45.Fk Electrodes
82.47.Uv Electrochemical capacitors; supercapacitors
84.32.Tt Capacitors
84.60.Ve Energy storage systems, including capacitor banks

Nanoscale characterization and metrology

Alain C. Diebold

J. Vac. Sci. Technol. A 31, 050804 (2013); http://dx.doi.org/10.1116/1.4807116 (10 pages)

Online Publication Date: 22 May 2013

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This paper will take a “From the Lab to the FAB” approach for discussing the measurements and applications of nanoscale characterization and metrology. The nanoscale dimensions of features found in semiconductor materials and devices provide many challenges for characterization of physical properties as well as measurements for process control. The use of multiple measurement methods results in a more complete determination of the properties so that structure–function relationships can be elucidated. Here, the authors use pseudomorphic Si1−xGex on Si(001), nanoscale films of Ni, and nanoscale Hf oxide films to illustrate this principle.
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61.46.-w Structure of nanoscale materials
68.55.-a Thin film structure and morphology
77.55.-g Dielectric thin films
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
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