Excitation Wavelength Dependence of Carrier Relaxation in Self-Assembled InAs Quantum Dots Embedded in Strain-Relaxed In0.35Ga0.65As Barrier Layers

Abstract

Excitation wavelength dependence (λ= 1350–1550 nm) of carrier relaxation was investigated for self-assembled InAs quantum dots (QDs) embedded in strain-relaxed In0.35Ga0.65As barriers grown on GaAs(100) substrates. Fast (τ∼12–17 ps) and slow (τ∼350 ps) decay components were observed in the time-resolved transmission change measurements by a pump-probe method. Decay time of the fast component becomes faster as the excitation wavelength is shortened, indicating that photo-generated carries in the smaller-size QDs more easily escape into the nonradiative centers arising from the crystal defects related to the lattice-mismatch. In addition, the slow decay component attributed to the radiative recombination process was strongly suppressed for the shorter wavelength excitation.