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Title: Elastic scattering by hot electrons and apparent lifetime of longitudinal optical phonons in gallium nitride

Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, the saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.
Authors:
 [1] ; ;  [2]
  1. Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)
  2. Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)
Publication Date:
OSTI Identifier:
22486301
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 26; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; BRILLOUIN ZONES; CARRIER DENSITY; COLLISIONS; ELASTIC SCATTERING; ELECTRON DENSITY; ELECTRON MOBILITY; ELECTRON TEMPERATURE; ELECTRONS; GALLIUM NITRIDES; MICROWAVE RADIATION; NOISE; PHONONS; SATURATION; TIME RESOLUTION; TRANSISTORS