Spectral concentration of thermal conductivity in GaN—A first-principles study
Abstract
We find using first-principles analysis of thermal conductivity (k) in isotopically pure Gallium nitride (GaN) that almost 60% of the heat is conducted by phonons in a very narrow frequency range of 5–7 THz (spanning only 9% of the frequencies in GaN). This spectral focusing of thermal conductivity is found to be due to a combination of two effects—a large increase in lifetimes of phonons through suppression of anharmonic scattering in the 5–7 THz frequency range coupled with a large phonon density of states at the same frequencies. Understanding of the effect is provided by solving the phonon Boltzmann transport equation in the single mode relaxation time approximation along with the use of harmonic and anharmonic force constants derived from density functional theory. The results can have important implications for engineering the thermal performance of devices based on GaN.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 18, 2018
- Source ID
- 10.1063/1.5026903
Entities
People
- Gang Chen
- Jivtesh Garg
- Tengfei Luo
Organizations
- Defense Advanced Research Projects Agency
- Massachusetts Institute of Technology
- Office of Naval Research
- University of Notre Dame
- University of Oklahoma