Microstructure of the deep level defect E1/E2 in 6H silicon carbide (Abstract)

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Experimental study and modeling of the influence of screw dislocations on the performance of Au/n-GaN Schottky diodes

The influence of screw dislocations on the performance of Au/n-GaN Schottky diodes was investigated. The current-voltage (I-V) characteristics of the diodes fabricated on different GaN templates grown by metallorganic chemical vapor deposition on sapphire substrates were studied. It was shown that these dislocations result in the lowering of the barrier height in the localized regions.published_or_final_versio

Deep level transient spectroscopy study of particle irradiation induced defects in n-6H-SiC (Abstract)

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Deep level transient spectroscopic study of neutron-irradiated n-type 6H-SiC

A study of neutron-irradiated n-type 6H-SiC using deep level transient spectroscopy was presented. 100- 1600°C isochronal annealing was performed on the as-irradiated samples with each of the annealing steps to investigate the thermal annealing behavior. Thermal generation of deep levels NE1- NE4 at annealing temperatures above 1400°C was observed.published_or_final_versio

Spatial distribution of carrier concentration in un-doped GaN film grown on sapphire (Abstract)

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Acceptors in undoped gallium antimonide

Undoped GaSb materials were studied by temperature dependent Hall (TDH) measurements and photoluminescence (PL). The TDH data reveals four acceptor levels (having ionization energies of 7meV, 32meV, 89meV and 123meV) in the as-grown undoped GaSb samples. The 32meV and the 89meV levels were attributed to the GaSb defect and the VGa-related defect. The Ga Sb defect was found to be the important acceptor responsible for the p-type nature of the present undoped GaSb samples because of its abundance and its low ionization energy. This defect was thermally stable after the 500°C annealing. Similar to the non-irradiated samples, the 777meV and the 800meV PL signals were also observed in the electron irradiated undoped GaSb samples. The decrease of the two peaks' intensities with respect to the electron irradiation dosage reveals the introduction of a non-radiative defect during the electron irradiation process, which competes with the transition responsible for the 777meV and the 800meV PL peaks.published_or_final_versio

Nature of the acceptor responsible for p-type conduction in liquid encapsulated Czochralski-grown undoped gallium antimonide

The acceptors in undoped liquid encapsulated Czochralski (LEC)-grown GaSb were investigated using temperature dependent Hall (TDH) and positron lifetime spectroscopy measurements. TDH measurements were performed on nonirradiated and electron irradiated undoped samples. The 34 meV acceptor was found to be the important one responsible for the p-type conduction in nonirradiated and the e--irradiated undoped materials annealed at temperatures up to 500°C. This acceptor was not related to any VGa-related defect detected and was most likely the GaSb antisite.published_or_final_versio

Current transport property of n-GaN/n-6H-SiC heterojunction: Influence of interface states

Heterostructures of n-GaNn-6H-SiC grown by hydride vapor phase epitaxy (HVPE) and molecular-beam epitaxy (MBE) are characterized with the current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) techniques. Using different contact configurations, the I-V results reveal a rectifying barrier in the n-GaNn-6H-SiC heterostructures. When GaN is negatively biased, the current is exponentially proportional to the applied voltage with the built-in barrier being 0.4-1.1 eV for the HVPE samples and 0.5 eV for the MBE sample. DLTS measurements reveal intense band-like deep level states in the interfacial region of the heterostructure, and the Fermi-level pinning by these deep level defects is invoked to account for the interfacial rectifying barrier of the heterostructures. © 2005 American Institute of Physics.published_or_final_versio

Deep-level defects in n-type 6H silicon carbide induced by He implantation

Defects in He-implanted n -type 6H-SiC samples have been studied with deep-level transient spectroscopy. A deep-level defect was identified by an intensity with a logarithmical dependence on the filling pulse width, which is characteristic of dislocation defects. Combined with information extracted from positron-annihilation spectroscopic measurements, this defect was associated with the defect vacancy bound to a dislocation. Defect levels at 0.380.44 eV (E1 E2), 0.50, 0.53, and 0.640.75 eV (Z1 Z2) were also induced by He implantation. Annealing studies on these samples were also performed and the results were compared with those obtained from e- -irradiated (0.3 and 1.7 MeV) and neutron-irradiated n -type 6H-SiC samples. The E1 E2 and the Z1 Z2 signals found in the He-implanted sample are more thermally stable than those found in the electron-irradiated or the neutron-irradiated samples. © 2005 American Institute of Physics.published_or_final_versio

The depth-profiled carrier concentration and scattering mechanism in undoped GaN film grown on sapphire

The carrier concentration and scattering mechanism in undoped GaN film grown on sapphire were investigated. The film was grown on sapphire using metal organic chemical vapor deposition (MOCVD). Confocal micro-Raman spectroscopic measurements and temperature-dependant Hall (TDH) measurements were performed for the study of the depth distribution of the carrier density across the GaN film. The existence of a nonuniform spatial distribution of free carriers in the film with a highly conductive layer of ∼1 μm thickness near the GaN sapphire boundary was confirmed from the study. The electron mobility limiting effect of nitrogen vacancies on GaN bulk film was also discussed.published_or_final_versio