Suppression of intervalley scattering in Ga(As)Sb quantum wells

Femtosecond time-resolved reflectivity was measured near the 1.55 mum absor ption edge of several GaAsxSb1-x/AlSb quantum well samples. On the basis of differences in the reflectivity recovery kinetics and plateau values, we d educe that Gamma -L intervalley scattering can be effectively suppressed fo r x greater than or equal to0.19. This is consistent with calculations inco rporating confinement and strain effects which give L-Gamma energy separati ons of 29 (x=0) and 109 meV (x=0.19). Suppression of intervalley scattering can lead to increased internal quantum efficiency and higher carrier mobil ity in 1.55 mum based devices. (C) 2000 American Institute of Physics. [S00 03-6951(00)04244-3].