Scattering of g -process longitudinal optical phonons at hotspots in silicon

S. Sinha, P. K. Schelling, S. R. Phillpot, K. E. Goodson

Research output: Contribution to journalArticlepeer-review

Abstract

Transistors with gate lengths below 100 nm generate phonon hotspots with dimensions on the order of 10 nm and peak power densities of about 50 Wμm3. This work employs molecular dynamics to investigate the impact of lattice energy density on phonon scattering at the hotspot. The hotspot studied in this work consists of longitudinal optical phonons involved in the g -type intervalley scattering of conduction electrons in silicon. A comparison of the decay modes in hotspots with high and moderate energy densities reveals that the decay mechanisms are the same but the relaxation rates differ. Scattering occurs through a three phonon process of the form LO→LA+TA, involving the zone-edge transverse acoustic modes. An increase in the energy density from a moderate value of 5 to 125 Wμm3 changes the relaxation time from 79 to 16 ps, approximately proportional to the the maximum initial amplitude of the phonons. This work improves the accuracy of the scattering rates of optical phonons and helps in advancing the electro-thermal modeling of nanotransistors.

Original languageEnglish (US)
Article number023702
JournalJournal of Applied Physics
Volume97
Issue number2
DOIs
StatePublished - Jan 15 2005
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy

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