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Author Reddy, Pramod ♦ Washiyama, Shun ♦ Kaess, Felix ♦ Hernandez-Balderrama, Luis H. ♦ Haidet, Brian B. ♦ Alden, Dorian ♦ Franke, Alexander ♦ Sarkar, Biplab ♦ Kohn, Erhard ♦ Collazo, Ramon ♦ Sitar, Zlatko ♦ Hayden Breckenridge, M.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ ALUMINIUM NITRIDES ♦ BENDING ♦ CAPACITANCE ♦ CHEMICAL VAPOR DEPOSITION ♦ COMPARATIVE EVALUATIONS ♦ DIELECTRIC MATERIALS ♦ ELECTRIC POTENTIAL ♦ ELECTRONS ♦ FERMI LEVEL ♦ GALLIUM NITRIDES ♦ HETEROJUNCTIONS ♦ INTERFACES ♦ PASSIVATION ♦ SILICON ♦ SILICON NITRIDES ♦ TEMPERATURE RANGE 0400-1000 K ♦ X RADIATION ♦ X-RAY PHOTOELECTRON SPECTROSCOPY
Abstract In this work, we employed X-ray photoelectron spectroscopy to determine the band offsets and interface Fermi level at the heterojunction formed by stoichiometric silicon nitride deposited on Al{sub x}Ga{sub 1-x}N (of varying Al composition “x”) via low pressure chemical vapor deposition. Silicon nitride is found to form a type II staggered band alignment with AlGaN for all Al compositions (0 ≤ x ≤ 1) and present an electron barrier into AlGaN even at higher Al compositions, where E{sub g}(AlGaN) > E{sub g}(Si{sub 3}N{sub 4}). Further, no band bending is observed in AlGaN for x ≤ 0.6 and a reduced band bending (by ∼1 eV in comparison to that at free surface) is observed for x > 0.6. The Fermi level in silicon nitride is found to be at 3 eV with respect to its valence band, which is likely due to silicon (≡Si{sup 0/−1}) dangling bonds. The presence of band bending for x > 0.6 is seen as a likely consequence of Fermi level alignment at Si{sub 3}N{sub 4}/AlGaN hetero-interface and not due to interface states. Photoelectron spectroscopy results are corroborated by current-voltage-temperature and capacitance-voltage measurements. A shift in the interface Fermi level (before band bending at equilibrium) from the conduction band in Si{sub 3}N{sub 4}/n-GaN to the valence band in Si{sub 3}N{sub 4}/p-GaN is observed, which strongly indicates a reduction in mid-gap interface states. Hence, stoichiometric silicon nitride is found to be a feasible passivation and dielectric insulation material for AlGaN at any composition.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-04-14
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 119
Issue Number 14


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