[citation needed] Between 524 °C and 942 °C (the melting points of pure InSb and InAs, respectively), InAsSb can exist at a two-phase liquid-solid equilibrium, depending on temperature and average composition of the alloy.
[1][2] InAsSb possesses an additional miscibility gap at temperatures below approximately 503 °C.
[2] This means that intermediate compositions of the alloy below this temperature are thermodynamically unstable and can spontaneously separate into two phases: one InAs-rich and one InSb-rich.
This limits the compositions of InAsSb that can be obtained by near-equilibrium growth techniques, such as LPE, to those outside of the miscibility gap.
[1] However, compositions of InAsSb within the miscibility gap can be obtained with non-equilibrium growth techniques, such as MBE and MOVPE.
By carefully selecting the growth conditions and maintaining relatively low temperatures during and after growth, it is possible to obtain compositions of InAsSb within the miscibility gap that are kinetically stable.
The following empirical relationship has been suggested for the direct bandgap of InAsSb in eV as a function of composition (0 < x < 1) and temperature (in Kelvin):[1]
This equation is plotted in the figures, using a suggested bowing parameter of C = 0.75 eV.
Slightly different relations have also been suggested for Eg as a function of composition and temperature, depending on the material quality, strain, and defect density.
[citation needed] Because of its small direct bandgap, InAsSb has been extensively studied over the last few decades, predominantly for use in mid- to long-wave infrared photodetectors that operate at room temperature and cryogenic temperatures.