The surface chemical properties of a GaAs layer grown by molecular beam epitaxy were investigated by photoluminescence (PL) and photoreflectance (PR) measurements. While the intensity of the PL spectra for the sulfur-treated GaAs, using a (NH4)2Sx solution, increased 75 times compared to that for the as-grown GaAs, the peaks for the as-grown GaAs measured by PR vanished after a sulfur treatment. These results indicate that the surface state acting as the nonradiative recombination centers was passivated by the sulfur. The chemical adsorption behavior resulting from the sulfur is discussed.
Photoluminescence (PL) and photoreflectance (PR) measurements have been performed to investigate the intermixing behavior of Al and Ga in GaAs/AlAs multiple quantum wells (MQWs) grown by molecular-beam epitaxy and treated by rapid thermal annealing. These results indicate that the magnitude of the disordering for a GaAs/AlAs MQW increases as the layer thickness increases. When the GaAs/AlAs MQWs with layer thicknesses of 34 Å are annealed at 950 °C for 10 s, the GaAs/AlAs MQWs are totally intermixed, resulting in a formation of an Al0.45Ga0.55As alloy. For the intermixed GaAs/AlAs MQWs, PL spectra show dominantly the Γ-valley direct transition, and PR signals show that the peaks originating from the interband transitions disappear. The observed increases of the full width at half-maximum (FWHM) in the PL spectra for the annealed GaAs/AlAs MQWs originate from the nonuniformity of the intermixing as a function of depth, and the decrease of FWHM in the PL spectra for the GaAs/AlAs MQWs annealed for longer times is due to the formation of Al0.45Ga0.55As alloys in the GaAs/AlAs MQWs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.