Electron Scattering Rates in AlGaN/GaN Quantum Wells for 1.55-µm Inter-Subband Transition

Abstract

Electron scattering rates in AlGaN/GaN QWs for the 1.55-µm inter-subband transition at room temperature are calculated. The inter-subband scattering time, which is dominated by the longitudinal optical (LO) phonon scattering, is as short as about 100 fs. The intra-subband LO-phonon scattering rate, the electron-electron scattering rate, and the ionized impurity scattering rate are greater than those in (In)GaAs QWs. This causes a short dephasing time of about 10 fs, which reduces the peak value of the third-order nonlinear susceptibility but broadens its spectral width. Even if the band nonparabolicity is taken into consideration, ultrafast response of the inter-subband optical nonlinearity in GaN QWs is little affected by the delay in intra-subband energy relaxation caused by non-equilibrium phonons.