Marked reduction in photocarrier lifetime by erbium doping into self-assembled InAs quantum dots embedded in strain-relaxed InGaAs barriers

Abstract

Effects of erbium doping on photocarrier lifetime have been investigated for self-assembled InAs quantum dots (QDs) embedded in strain-relaxed In0.35Ga0.65As barriers grown on (100) GaAs substrates by molecular beam epitaxy. Time-resolved transmission change measurements were performed on 20-layer stacks of the Er-doped InAs QDs at room temperature using 0.1ps laser pulses with the center wavelength of 1.5μm. Fast and slow decay components were observed in the temporal profile of each Er-doped InAs QD sample. The slow decay component attributed to the radiative recombination process in the QDs was well suppressed by increasing Er-doping density. Moreover, the decay time of the fast component due to the nonradiative process was markedly reduced by the incorporation of Er dopants during the QD formation. A decay time of 3.5ps was obtained for the Er-doped InAs QD sample with a sheet density of incorporated Er dopants per QD layer of 2.7×1013cm−2.