Temperature dependence of the photoluminescence emission from InAs quantum dots in a strained Ga_0.85In_0.15As quantum well

Abstract

Photoluminescence from InAs quantum dots in a strained Ga0.85In0.15As quantum well is investigated over a temperature range from 10 to 300 K using low intensity optical excitation. A rate equation model for the carrier dynamics is fitted to the experimental data obtained for the integrated intensity of the photoluminescence at different temperatures. It is found necessary to assume a potential barrier, possibly arising from the strain, at the interface between the dots and the quantum well that makes the carrier capture in dots less effective at low temperatures. In addition, two thermal escape mechanisms for carriers in the dots are identified that have the onsets at 110 K and 220 K, respectively. At low temperatures, the ground state photoluminescence has a large full width at half maximum, while at temperatures above 220 K, the full width decreases as emission from larger dots dominate. The activation energies for different carrier thermal escape channels are estimated using the solutions of the steady-state rate equation system.