Cascaded exciton emission of an individual strain-induced quantum dot

TL;DR

This paper investigates the cascaded exciton emission in individual strain-induced quantum dots, revealing detailed dynamics and confirming a three-step cascade model through experimental and theoretical analysis.

Contribution

It introduces a method to isolate single strain-induced quantum dots and demonstrates their cascaded emission behavior with a rate equation model.

Findings

Identification of unpolarized single, bi-, and triexciton emissions

Observation of time-dependent shifts in emission rise and decay times

Validation of a three-step cascade rate equation model

Abstract

Single strain-induced quantum dots are isolated for optical experiments by selective removal of the inducing InP islands from the sample surface. Unpolarized emission of single, bi- and triexciton transitions are identified by power-dependent photoluminescence spectroscopy. Employing time-resolved experiments performed at different excitation powers we find a pronounced shift of the rise and decay times of these different transitions as expected from cascaded emission. Good agreement is found for a rate equation model for a three step cascade.