Energy relaxation of hot electrons in III-N bulk materials

Abstract

Energy relaxation of the hot electrons in GaN, AlN and InN is investigated and compared based on a simple analytical model with both the hot-phonon effect (HPE) and the nonparabolicity of the conduction band taken into account. The impact of the HPE on the energy relaxation time is estimated by using various optical phonon lifetimes. The calculation results show that for this group of III nitrides, the energy relaxation time first falls rapidly and then saturates with the increasing electron temperature, and is higher at a high electron density. The presence of the HPE slows down the power dissipation and increases the energy relaxation time of the hot electrons of the density 1 × 1018 cm−3 (or 1 × 1019 cm−3) by around one or two orders of magnitude at an electron temperature within 3000 K. In particular, the saturated energy relaxation times are 0.12 ps in the bulk GaN, 22 fs in AlN and 26 fs in InN for an electron density of 1 × 1018 cm−3, which imply a rather weak HPE in the AlGaN and AlInN alloys.