Hot carrier photoluminescence from strained In xGa 1− xAs/GaAs single quantum wells

Abstract

Strained single quantum well (SSQW) structures of In x Ga 1- x As/GaAs, x = 0.14−0.22 and 100 Å thick, have been grown by molecular beam epitaxy. Layer thicknesses and compositions were independently calibrated by RHEED oscillations, surface profiling and photoluminescence measurements. The thickness of all SSQWs are below the critical one for development of interface defects. Photoexcitation of hot carriers by short and intense laser pulses shows excess luminescence in a high energy tail enabling determination of the carrier temperature. Carrier relaxation times are deduced by time-resolved measurements using ps excitation. The indium composition in the SSQWs has a significant effect on the carrier temperature and relaxation times. Thus in 100 Å thick wells the carrier temperature is 270 K for x = 0.14 and 360 K for x = 0.22 (at an excitation intensity of 1×10 4 W/cm -2). The hot carrier effect is absent in MBE-grown lattice relaxed bulk layers of the same composition.