Carrier thermal escape in families of InAs/InP self-assembled quantum dots

TL;DR

This study models and analyzes the thermal escape mechanisms of carriers in InAs/InP quantum dots, revealing that carriers mainly escape via thermal emission to the wetting layer, with correlated electron-hole pairs exiting together.

Contribution

A coupled rate-equation model was developed to accurately describe carrier thermal escape in quantum dots, matching experimental data with a unified parameter set.

Findings

Main escape mechanism is thermal emission to the wetting layer.

Activation energy is about half the energy difference between quantum dots and wetting layer.

Electrons and holes exit as correlated pairs.

Abstract

We investigate the thermal quenching of the multimodal photoluminescence from InAs/InP (001) self-assembled quantum dots. The temperature evolution of the photoluminescence spectra of two samples is followed from 10 K to 300 K. We develop a coupled rate-equation model that includes the effect of carrier thermal escape from a quantum dot to the wetting layer and to the InP matrix, followed by transport, recapture or non-radiative recombination. Our model reproduces the temperature dependence of the emission of each family of quantum dots with a single set of parameters. We find that the main escape mechanism of the carriers confined in the quantum dots is through thermal emission to the wetting layer. The activation energy for this process is found to be close to one-half the energy difference between that of a given family of quantum dots and that of the wetting layer as measured by photoluminescence excitation experiments. This indicates that electron and holes exit the InAs quantum dots as correlated pairs.