Molecular Beam Epitaxy Growth-Space Investigation of InAsBi and InGaAsBi on InAs

Highly mismatched alloys (HMA) have garnered increasing interest over the past few decades due to the promise of increased engineering flexibility in the design of advanced compound semiconductor heterostructure devices. Increased control over key device parameters such as lattice constant, bandgap, and band offsets opens the door to improved performance for a wide range of electronic and optoelectronic devices. However, the large miscibility gaps characteristic of HMA’s make these materials far more difficult to grow than traditional III-V alloys. Growth of dilute-bismuthides, in particular, has historically been plagued by bismuth surface segregation, resulting in droplet and alternate phase formation. However, if these growth challenges can be overcome, InAsBi, and its lattice-matched cousin, InGaAsBi, hold great promise for InAs-based mid-to-long wavelength infrared photodetectors; this material system benefits from having a controllable bandgap, a strong absorption coefficient, latticematched and super-lattice-free growth, and mature III-V processing, making it a significant competitor to the more established InSb, HgCdTe, and type-II GaSb/InAs material systems. By applying recent advances from molecular beam epitaxy (MBE) growth of GaAsBi [1] to the growth of InAsBi and InGaAsBi on InAs, we map out a growth space free of droplet and alternate phase formation in which the optical quality is significantly enhanced.