Thermally activated inter-dots carriers' transfer in InAs QDs with InGaAs underlying layer: Origin and dependence on the post-growth intermixing

Abstract

This paper reports on experimental and theoretical investigation of atyical temperature-dependent photoluminescence properties of InAs quantum dots in close proximity to InGaAs strain-relief underlying quantum well. The impact of a post-growth intermixing process on these properties has been studied. For the as-grown sample, the maximum of the emission band follows a sigmoidal function while the photoluminescence linewidth mimics a V-shape function as the temperature increases, from 11 to 300 K. These behaviors are attributed to thermally activated carrier transfer mechanisms within the inhomogenious distribution of quantum dots. These atypical behaviors are found to disappear progressively with the degree of intermixing and consequent narrowing of the dot size dispersion. The experimental results have been interpreted in the frame of the localized states ensemble model revealing that the large dots size distribution is the main origin of the observed anomalies. Furthermore, the calculations show that the quantum well continuum states act as a transit channel for the redistribution of thermally activated carriers.