AlGaSb/GaSb quantum wells grown on an optimized AlSb nucleation layer

Five-period AlGaSb/GaSb multiple quantum wells（MQW） are grown on a GaSb buffer.Through optimizing the AlSb nucleation layer,the low threading dislocation density of the MQW is found to be（2.50±0.91）×10;cm;in 1-μm GaSb buffer,as determined by plan-view transmission election microscopy（TEM） images.High resolution TEM clearly shows the presence of 90°misfit dislocations with an average spacing of 5.4 nm at the AlSb/GaAs interface,which effectively relieve most of the strain energy.In the temperature range from T = 26 K to 300 K,photoluminescence of the MQW is dominated by the ground state electron to ground state heavy hole（el-hhl） transition, while a high energy shoulder clearly seen at T>76 K can be attributed to the ground state electron to ground state light hole（el-lhl） transition.