Direct E0 energy gaps of bismuth-containing III–V alloys predicted using quantum dielectric theory

Quantum dielectric theory has been used to predict the direct E0 energy gaps of ternary and quaternary III–V semiconductor alloys containing up to ∼10 mol % InBi. The calculated composition dependence of E0 for InSb1−xBix is in good agreement with experimental results with a predicted semiconductor–semimetal transition (77 K) at x=0.124. E0 (77 K) values corresponding to infrared wavelengths of 8 to 12 μm are obtained at x=0.043–0.070, respectively, corresponding to lattice mismatches with InSb substrates in the range from 0.11% to 0.17%. The quaternary alloys InAs1−x−ySbxBiy and In1−xGaxSb1−yBiy also yield E0 values in this range with similar InBi contents while maintaining exact lattice match to InSb substrates. InAs1−xBix is proposed as a new alloy for spanning the wavelength range from 3 to 5 μm. The required x values range from 0 to 0.079 (measuring E0 at 77 K) and the maximum lattice mismatch with either InAs or GaSb substrates for these compositions is <0.31%. The related quaternary alloy In1−xGaxAs1−yBiy also spans the 3–5 μm wavelength range while maintaining lattice match with InAs or GaSb substrates.