Random alloy growth of AlAs_0.08Sb_0.92 on GaSb under high Group-V flux condition

The growth of AlAs(x)Sb(1-x )epilayers with x<0.1 is crucial for various optoelectronic device applications. However, achieving the desired alloy composition and lattice-matched condition remains challenging. In this study, the epitaxial growth of the random alloy AlAsSb on GaSb was investigated using molecular beam epitaxy. The objective was to determine the optimal growth condition to obtain AlAs0.08Sb0.92 on GaSb (lattice-matched to GaSb) with a high growth rate and under a high group-V/III beam equivalent pressure (BEP) ratio. The growth parameters, including the group-V/III BEP ratio, growth rate, and temperature, were studied to monitor the change in the structural properties of the AlAsSb epilayer. It was shown that the As incorporation in AlAsSb was higher than expected at high growth rate and under high Sb BEP condition. The results demonstrated that increasing the growth temperature while decreasing the As BEP did not significantly improve the crystal quality where the optimization of group-V/III BEP ratio and As BEP is effective to obtain AlAs0.08Sb0.92 on GaSb and enhance the crystal quality. The findings provide valuable insights into the growth dynamics of AlAsSb to achieve high quality and lattice-matched epilayers grown on GaSb which is well-suited for a range of optoelectronic applications.