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Author Koley, G. ♦ Spencer, M. G.
Sponsorship (US)
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Publisher The American Physical Society
Language English
Subject Keyword CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ ATOMIC FORCE MICROSCOPY ♦ DATA ♦ MICROSCOPY ♦ PHYSICS ♦ PROBES ♦ SURFACE POTENTIAL ♦ THICKNESS ♦ WORK FUNCTIONS
Abstract Surface potentials on GaN epilayers and Al{sub 0.35}Ga{sub 0.65}N/GaN heterostructures have been studied by scanning Kelvin probe microscopy (SKPM) in conjunction with noncontact atomic force microscopy. The dependence of the surface potential on doping in GaN films, as well as the variation of surface potential with Al{sub 0.35}Ga{sub 0.65}N barrier layer thickness has been investigated. The bare surface barrier height (BSBH), as measured by SKPM, is observed to decrease from {similar_to}1. 40{+-}0.1 eV to {similar_to}0.60{+-}0.1 eV with increasing doping in the GaN epilayers. Schottky barrier height calculated from the measurements of BSBH on n-GaN agrees very well with results from previous studies. We have also estimated the surface state density for GaN based on the measured values of BSBH. The semiconductor {open_quotes}work function{close_quotes} at the Al{sub 0.35}Ga{sub 0.65}N surface (in heterostructure samples) is observed to decrease by {similar_to}0.60 eV with increase in barrier layer thickness from {similar_to}50 to {similar_to}440 Aa. A simple model considering the presence of a uniform density of charged acceptors in the Al{sub 0.35}Ga{sub 0.65}N layer is proposed to explain the observed decreasing trend in work function. {copyright} 2001 American Institute of Physics.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2001-07-01
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 90
Issue Number 1


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