ELECTRON-SCATTERING RATES IN ALGAN GAN QUANTUM-WELLS FOR 1.55-MU-M INTERSUBBAND TRANSITION/

Electron scattering rates in AlGaN/GaN QWs for the 1.55-mu m inter-sub band transition at room temperature are calculated. The inter-subband scattering time, which is dominated by the longitudinal optical (LO) p honon scattering, is as short as about 100 fs. The intra-subband LO-ph onon scattering rate, the electron-electron scattering rate, and the i onized 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 i ts spectral width. Even if the band nonparabolicity is taken into cons ideration, ultrafast response of the inter-subband optical nonlinearit y in GaN QWs is little affected by the delay in intra-subband energy r elaxation caused by non-equilibrium phonons.