Influence of capping-layer growth mode on the photoluminescence of InAs quantum dots in silicon

Subject of study . In this study, Si epitaxial layers with embedded indium arsenide (InAs) quantum dots (QDs) were investigated. Aim of study . The aim was to experimentally examine the luminescent characteristics of InAs QDs in a Si matrix. In addition, the dependence of the photoluminescence (PL) intensity of the heterostructure on the temperature and growth method of the Si capping layer was investigated. Method. Si epitaxial layers with embedded InAs QDs were fabricated via molecular beam epitaxy. The optical properties in the range of 10–120 K were studied using low-temperature PL spectroscopy. Main results. The influence of the growth conditions of the Si capping layer on the optical properties of heterostructures with submonolayer InAs QDs embedded in a Si matrix was investigated. A PL signal at 1.65 µm, originating from submonolayer QDs, was obtained at temperatures up to 120 K. The two-stage Si overgrowth method for InAs nanoislands increased the PL intensity by improving the crystalline quality of the heterostructures. Based on an analysis of the temperature dependence, the activation energy of electrons confined in the QD potential well was estimated to be 30 meV, which was comparable with the thermal energy at room temperature (25 meV). Practical significance. The results obtained from the optical property analysis of heterostructures with submonolayer InAs QDs can serve as a basis for developing new optoelectronic devices based on Si technologies.