Improved III-V Antimonide-Based Superlattice Materials From Growth and Defect Modeling

Absorber layers based on strained layer superlattice (SLS) composed of III-V compound semiconductors (e.g. GaSb and InAs/Sb) are a promising sensor technology for infrared imaging; however, dark currents and short carrier lifetimes in SLS are still significant problems. It is presently suspected that the short carrier lifetimes and some dark current arise due to a native point defect, possibly the Ga/In antisites (a III-group atom on the V-group sublattice), creating a mid-gap state within the SLS band gap that facilitates Shockley-Read-Hall generation/recombination. Sivananthan Laboratories, Inc. proposes to use molecular dynamics simulations to evaluate the types and distributions of defects as a function of MBE growth parameters, and tight binding electronic structure calculations to evaluate the effect of defects on lifetimes and hence dark currents, thus producing a fully computational method to relate MBE process parameters to device performance. Possible growth process improvements will be considered, based on the identified deleterious defects and associated process parameters, and tested using the proposed computational method. Experiments will then be performed to verify the theoretical understanding and optimize a growth process based on the theoretical predictions.