Recombination dynamics of type-II excitons in (Ga,In)As/GaAs/Ga(As,Sb) heterostructures

TL;DR

This study investigates the recombination dynamics of type-II excitons in complex heterostructures using photoluminescence spectroscopy, revealing temperature-dependent behaviors and the importance of exciton relaxation and hopping in disordered materials.

Contribution

It introduces a detailed analysis of type-II exciton dynamics in (Ga,In)As/GaAs/Ga(As,Sb) heterostructures, emphasizing the role of localized states and temperature effects.

Findings

Type-II luminescence shows non-exponential decay below 70K.

Exciton relaxation and hopping in disordered Ga(As,Sb) are key to exciton dynamics.

Temperature influences the recombination behavior of excitons.

Abstract

(Ga,In)As/GaAs/Ga(As,Sb) multi-quantum well heterostructures have been investigated using continuous wave and time-resolved photoluminescence spectroscopy at various temperatures. A complex interplay was observed between the excitonic type-II transitions with electrons in the (Ga,In)As well and holes in the Ga(As,Sb) well and the type-I excitons in the (Ga,In)As and Ga(As,Sb) wells. The type-II luminescence exhibits a strongly non-exponential temporal behavior below a critical temperature of Tc = 70K. The transients were analyzed in the framework of a rate-equation model. It was found that the exciton relaxation and hopping in the localized states of the disordered ternary Ga(As,Sb) are the decisive processes to describe the dynamics of the type-II excitons correctly.