Vertical stacks of InAs quantum dots embedded into short-period AlAs/GaAs superlattice

摘要

Single layers and vertical stacks of coherent InAs quantum dots (QDs) embedded into GaAs/AlAs short-period superlattice (SPSL) were grown by molecular beam epitaxy at 475 °C. Photoluminescence (PL), atomic force microscopy and transmission electron microscopy were used to analyze the structure and optical properties of QD structures. Well-aligned vertical stacks of QDs were observed for the spacings up to 12 nm, though the electronic coupling was low at large spacings as measured by the shift of the PL band. Reduction of thermal quenching of the QD luminescence band was observed due to increased band gap of the barrier material Multilayer QD stacks showed wider dispersion of sizes and higher rate of nonradiative recombination, but exhibited similar PL efficiency and thermal quenching as the single QD layers. Use of SPSL allowed us to obtain a multiple-plane QD active media with the emission band centered below 1000 nm.