Concepedia

Abstract

Photoluminescence and absorption measurements were carried out on quaternary Ga0.75In0.25As0.04Sb0.96 /Al0.22Ga0.78As0.02Sb0.93 strained multiple quantum well (MQW) structure grown by molecular-beam epitaxy to investigate its band offsets and subband behavior. Strong luminescence and well-resolved excitonic absorption peaks are observed even at room temperature, which is indicative of good quality of our quaternary sample. By fitting the experimental results with the theoretical calculations, we find that the light holes are in Ga0.75In0.25As0.04Sb0.98 well regions (type I MQW) and the conduction-band offset ratio Qc=0.66±0.01. The transition from type I to type II for light holes may occur for the composition of x≤0.70 in GaxIn1−xAs0.04Sb0.96/ Al0.22Ga0.78As0.02Sb0.98 system.