Properties of photoluminescence in type-II GaAsSb/GaAs multiple quantum wells

Abstract

The optical properties of type-II GaAsSb/GaAs multiple quantum wells were investigated by photoluminescence. It was found that the peak position of photoluminescence (PL) spectra shows a giant blueshift under a moderate optical excitation level. As the pumping intensity increases further, the saturation of the peak position was observed. The giant blueshift can be interpreted in terms of the band-bending effect due to the spatially photoexcited carriers in a type-II alignment. The saturation effect was attributed to the creation of an energy barrier induced by photocarriers, which prevents the charge transfer. The change of integrated photoluminescence intensity with increasing excitation intensity is also consistent with the band-bending model. In addition, the temperature dependence of the PL spectra reveals that the thermal escape of electrons from the GaAs well into the GaAsSb barrier is responsible for the PL quenching.

Investigation of Localized Electric Field in the Type-II InAs/GaAsSb/GaAs Structure

“…In order to analyze the tendency of F , we consider the electric field induced by photo-excited carriers. The strong localized carriers near the interface form a charged plane and, correspondingly, produce an approximately triangular well with an electric-field strength of [5,6]:…”

“…3b shows that for type-II system the periods of FKOs were broadened with increase of I ex . It means that the F also increases because confined carriers induce the localized field due to the band bending effect caused by the spatially separated photo-excited carriers in type-II alignment [5,6].…”

“…In this type-II system, optical properties have been studied in many groups using photoluminescence (PL) measurements [5,6]. It shows that a significant blue-shift of the peak energy occurs under a moderate excitation power, which can be well explained by the band bending effect due to the spatially separated photo-excited carrier in type-II band alignment.…”

“…In addition, the separated charges by the band bending effect also induces localized electric field (F ). This F can be calculated by using theory of approximate triangular well [5,6]. However, it is difficult and complicated to obtain the value of F experimentally.…”

Heterostructured III-V Nanowires with Mixed Crystal Phases Grown by Au-Assisted Molecular Beam Epitaxy

“…The large blue shift can be attributed to the band filling and band bending effect as the excitation intensity increases (Chiu et al, 2002;Dinu et al, 2003). The spatially separated electrons and holes create an electric field at the GaAsSb/GaAs interface that results in band bending as the excitation density increases.…”