Elastic scattering by hot electrons and apparent lifetime of longitudinal optical phonons in gallium nitride
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 28, 2015
- Source ID
- 10.1063/1.4938745
Entities
People
- Jacob B Khurgin
- Sanyam Bajaj
- Siddharth Rajan
Organizations
- Johns Hopkins University
- Office of Naval Research
- Ohio State University