Compositional Control of the Mixed Anion Alloys in Gallium-Free InAs/InAsSb Superlattice Materials for Infrared Sensing (Postprint)

Gallium Ga-free InAsInAsSb superlattices SLs are being actively explored for infrared detector applications due to the long minority carrier lifetimes observed in this material system. However, compositional and dimensional changes through antimony Sb segregation during InAsSb growth can significantly alter the detector properties from the original design. At the same time, precise compositional control of this mixed-anion alloy system is the most challenging aspect of Ga-free SL growth. In this study, the authors establish epitaxial conditions that can minimize Sb surface segregation during growth in order to achieve high-quality InAsInAsSb SL materials. A nominal SL structure of 77 InAs35 InAs0.7Sb0.3 that is tailored for an approximately six-micron response at 150 K was used to optimize the epitaxial parameters. Since the growth of mixed-anion alloys is complicated by the potential reaction of As2 with Sb surfaces, the authors varied the deposition temperature Tg under a variety of Asx flux conditions in order to control the As2 surface reaction on a Sb surface.