J Hamazaki, K Ikuno, H Takahashi, H Kunugita, K Ema, A Kikuchi, K Kishino
Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX 5725 265-274 2005年
We have investigated the ultrafast relaxation dynamics of intersubband transition (ISBT) in GaN/AIN, using a two-color pump-probe technique, in a wide energy range around the optical communication wavelength. We suggest that the origin of the signal depends on the relation between the pump and probe pulse energies. We have observed an ultrafast induced absorption signal and a slow negative component which are due to the absorption of electrons during intra-subband scattering and a carrier cooling process with a hot-phonon effect, respectively. Moreover, we clarify the origin of the inhomogeneous broadening width of the ISBT and of the intrinsic absorption width of ISBT from the detailed analyses of the result. We have reproduced the relaxation dynamics by a numerical calculation to confirm this interpretation of ISBT relaxation dynamics.