Molecular Beam Epitaxy\nof InAsSbBi Lattice-Matched\nto InSb toward Long-Wave Infrared Sensing

InSb-based dilute-bismide alloys\npresent a unique opportunity to\nspan the entirety of the long-wave infrared with a bulk, lattice-matched\nIII–V alloy that boasts greatly reduced toxicity compared to\nthe current state-of-the-art, Hg<sub>1–<i>x</i></sub>Cd<sub><i>x</i></sub>Te. By incorporating both bismuth\nand arsenic in the appropriate proportions, we demonstrated InAs<sub>0.004</sub>Sb<sub>0.983</sub>Bi<sub>0.013</sub> lattice-matched to\ncommercially available InSb substrates. A kinetically limited growth\nregime that combined low substrate temperatures, V/III flux ratios\nnear unity, and a relatively fast growth rate, mitigated phase separation\nand resulted in films with excellent structural and optical quality.\nIn particular, the bismuth incorporation was estimated to be approximately\n95% substitutional and photoluminescence from the alloy was observed\nat elevated temperatures up to 400 K exhibiting significant wavelength\nextension beyond that of InSb, out to 7.6 μm at room temperature.\nFurthermore, the first antimony-rich InAs<sub><i>y</i></sub>Sb<sub>1–<i>x</i>–</sub><i><sub>y</sub></i>Bi<sub><i>x</i></sub> photodetector was fabricated\nand showed a longer cutoff wavelength than that of an InSb control\ndetector due to the bandgap reduction caused by bismuth and arsenic\nincorporation. This highlights that emission and detection from InAs<sub>0.004</sub>Sb<sub>0.983</sub>Bi<sub>0.013</sub> have accessed the\nlongest wavelengths of any lattice-matched, bulk III–V alloy\nto date. Altogether, these results demonstrate the strong potential\nof InAs<sub><i>y</i></sub>Sb<sub>1–<i>x</i>–</sub><i><sub>y</sub></i>Bi<sub><i>x</i></sub> for high-performance optoelectronic devices operating across\nthe long-wave infrared.