Defect Creation in InGaAs/GaAs Multiple Quantum Wells – II. Optical Properties

Abstract

a b s t r a c tThe optical properties of three sets of InGaAs/GaAs multiple quantum well (MQW) structures grown by molecular beam epitaxy and previously characterized by x-ray diffraction for crystal perfection were investigated. The correlations between growth conditions, crystal defects, and optical properties are discussed. Evaluation of the relative importance of non-radiative Shockley-Read-Hall (SRH) recombination was carried out according to a method presented herein. The optimal deposition temperature was determined based on both proper carrier confinement in the nanostructures and the least non-radiative recombination. Growing below this temperature increased SRH-recombination whereas higher growth temperatures led to carrier localization in local band edge minima. Varying the MQW periodicity and MQW period allowed the study of their effects on the strength of SRH-recombination. MQW periodicity results are explained in the frame of a cumulative deterioration effect with continued epitaxial growth, while MQW period data shows correlations between relaxation of the initial elastic stress and SRHstrength. Limitations of the underlying model for SRH-analysis are pointed out.

Investigation of the growth temperature on indium diffusion in InGaAs/GaAsP multiple quantum wells and photoelectric properties

“…Because more impurities are incorporated into MQWs, the crystal quality gets worse at low growth temperature, which seriously affects the luminous intensity of device. 37 Increase the growth temperature to 650 C, which can enhance the PL intensity and narrow FWHM, resulting in better interface quality and optical properties. However, further increase in growth temperature (680 C) results in decreased PL intensity and broadened FWHM probably because of the formation of quaternary InGaAsP thin layers by indium diffusion between the upper interface of InGaAs/ GaAsP in growth direction, so MQWs interface quality deteriorates and crystal defects are introduced.…”

Mode-locking Instabilities for High-Gain Semiconductor Disk Lasers Based on Active Submonolayer Quantum Dots

“…The carrier lifetime in SDLs gives an important indication of the nonradiative losses and represents a crucial parameter for achieving high optical-to-optical pump efficiency in modelocked operation [40,41]. To measure and compare the carrier lifetimes of SML QDs, SK QDs, and QWs, we use a degenerate pump-probe setup with 130-fs pulses and a tunable center pump-probe wavelength, set to the respective PL-maximizing wavelengths of the analyzed gain media.…”

Defect creation in InGaAs/GaAs multiple quantum wells–I. Structural properties

“…Observations are interpreted in the framework of a model describing defect creation as a multi-stage process, starting from accommodation of initial elastic stress and point defect (PD) creation on the growth front, followed by inward diffusion and accumulation at pre-dislocation clusters, and finally transformation to extended defects in the volume of epitaxial structure [10][11][12]. The crystalline properties of these structures as dependent on growth conditions are related to optical properties in the companion paper [13].…”