Abnormal temperature dependent photoluminescence of excited states of InAs/GaAs quantum dots: Carrier exchange between excited states and ground states

Abstract

This paper presents detailed studies on the temperature dependent photoluminescence (PL) of excited states (ES) of self-assembled InAs/GaAs quantum dots. Two abnormal temperature dependent characteristics of ES have been observed: first is the strong broadening of PL linewidth with increasing temperature from 15 to 300 K. Second, the intensity ratio of ES to ground states (GS) increases with raising temperature under all measured excitation powers. Such peculiarities could be well explained by the thermal carrier exchange between GS and ES. Taking into account the GS-ES carrier exchange, an improved carrier equation model is adopted to describe the temperature dependence of intensity ratio of ES to GS. The temperature dependent carrier population of ES is further discussed based on the simulation results.