Doping effect on photocarrier lifetime in InAs quantum dots with strain-relaxed InGaAs barriers grown by molecular beam epitaxy

We have studied effects of Si and Be δ-doping on photocarrier lifetime in self-assembled InAs quantum dots (QDs) with strain-relaxed In0.35Ga0.65As barriers grown on (1 0 0) GaAs substrates by molecular beam epitaxy. Relaxation of photocarriers generated in the QDs was characterized by time-resolved transmission change measurements at room temperature. Fast and slow decay components were observed in the temporal profile of each QD sample at an excitation wavelength of View the MathML source. A slow decay component attributed to the radiative recombination process in the QDs was rather suppressed by Be δ-doping after the QD formation. On the other hand, Si δ-doping resulted in shortening of the decay time of the fast component due to the nonradiative process arising from the crystal defects related to the lattice-mismatch. The decay time observed in the Si δ-doped QD sample was 9 ps, which was the half of those (18 ps) observed in the undoped and Be δ-doped QD samples.