Quantitative study of the effect of deposition temperature on antimony incorporation in InAs/InAsSb superlattices

InAs/InAsSb superlattices (SLs) are being actively explored for infrared detector applications owing to their superior carrier lifetimes. However, antimony (Sb) segregation during growth can alter the properties of the grown material. In this study, using X-ray energy dispersive spectrometry, authors quantify the compositional profile of individual layers and establish epitaxial parameters for high-quality InAs/InAsSb SL materials. Epitaxial conditions are determined for a nominal 7.7nm InAs/3.5nm InAs0.7Sb0.3 SL structure tailored for an approximately 6μm response at 150K. Since the growth of mixed anion alloys is complicated by the potential reaction of As2 with Sb surfaces, authors varied the deposition temperature (Tg) in order to control As2 surface reactions on Sb surfaces. Authors find that Sb incorporation is suppressed by 21%, with the increase of Tg from 395 to 440°C. This incorporation likely stems from Sb surface segregation during InAsSb layer growth that is driven by the As–Sb exchange mechanism, which can lead to significant compositional and dimensional deviations from the intended design.