Advanced High Operating Temperature Mid-Wave Infrared Sensors

The goal of this project is to reduce the cooling requirements of MWIR HgCdTe infrared photon detectors and improve detector performance at present-day cryogenic operating temperatures. During Phase I, we designed innovative Pn-N detectors and established the feasibility of growing the required HgCdTe-based structures by molecular beam epitaxy. Using this approach in a collaborative effort with the Army Research Laboratory and DRS Technologies, we demonstrated Auger suppression and high operating temperature devices based on LWIR MBE-grown HgCdTe. By employing a model similar to that previously developed, we propose to analyze two new approaches in Phase II to further reduce the dark currents: the implementation of novel PP+n-N+N and PP+p-N+N structures, and using p-type layers as absorbers. PP+n-N+N and PP+p-N+N structures benefit from reduced carrier injection into the absorber layers due to higher bandgap and higher doped barrier layers. Pp-N devices benefit from the slower Auger recombination in the absorber layers. The relative benefits and challenges of the four device architectures (Pn-N, Pp-N, PP+n-N+N and PP+p-N+N) will be evaluated. That architecture deemed to be most likely to be successful will be grown by MBE on large area silicon substrates. Non-equilibrium devices will be fabricated based on that architecture and fully characterized.