Effect of quantum confinement on lifetime of anharmonic decay of optical phonons in semiconductor nanostructures

Strong Hot Carrier Effects in Single Nanowire Heterostructures

We use transient Rayleigh scattering to study the thermalization of hot photoexcited carriers in single GaAs_0.7Sb_0.3/InP nanowire heterostructures. By comparing the energy loss rate in single core-only GaAs_0.7Sb_0.3 nanowires which do not show substantial hot carrier effects with the core-shell nanowires, we show that the presence of an InP shell substantially suppresses the longitudinal optical phonon emission rate at low temperatures which then leads to strong hot carrier effects.

Confined and interface optical phonon emission in GaN/InGaN double barrier quantum well heterostructures

In GaN-based high electron mobility transistors (HEMTs), the fast emission of longitudinal optical (LO) phonons can result in the formation of hot spots near the gate region where high electric fields produce hot electrons. In this work, we investigate the probability of phonon emission as a function of electron energy for confined and interface (IF) phonon modes for wurtzite GaN/InGaN/GaN heterostructures. Hot electrons radiate optical phonons which decay, anharmonically, into acoustic phonons that are essentially heat carriers. Herein, phonon engineering concepts are introduced which facilitate thermal management through the production of polar optical phonons. Some of the electrons near a semiconductor gate which manifests a strong electric field, are accelerated and the resulting hot electrons will produce confined and interface modes when the electrons are incident on a suitably-placed quantum well. This paper focuses on the production of confined and interface phonons. It is shown that interface modes may be preferentially produced which lead to elongated, lower-temperature hot spots.