High nitrogen composition–induced low interfacial roughness of GaAs0.978N0.022/GaAs multiple quantum wells grown through solid-source molecular beam epitaxy

Abstract

GaAs1−xNx/GaAs multiple quantum wells (MQWs) were grown on GaAs(001) substrates through solid-source molecular beam epitaxy under various nitrogen background pressures (NBPs), and the crystal quality at the interface of GaAs1−xNx and GaAs was investigated. X-ray diffraction and electron microscopy confirmed the low interface roughness of MQWs grown at a NBP of 5×10−6Torr. Surface morphology measurements revealed a smooth surface without whisker-like defect structures. The fabricated MQWs exhibited high photoluminescence intensity because of the reduction in surface recombination with high nitrogen incorporation. Raman spectroscopy confirmed the presence of N-like local vibrational mode, and this was attributed to the presence of phase separation in GaAsN alloys. Rapid thermal annealing improved photoluminescence intensity by 100-fold and substantially reduced full width at half maximum because of MQW homogenization. These results evidence the favorable crystal interface of GaAs0.978N0.022 alloys. Hence, GaAs0.978N0.022/GaAs MQWs grown under high pressure might be useful in fabricating optoelectronic devices.