High Performance Longwave Infrared (LWIR) HgCdTe on Silicon

The use of Si-based composite substrates for HgCdTe infrared focal plane arrays holds the promise of improved resolution, greater robustness and lower cost as compared to arrays that employ the present-day standard CdZnTe substrates. The principal challenge associated with the use of Si-based substrates is the presence of dislocations, created by the large lattice mismatch, that thread into the HgCdTe epilayers and thereby degrade device performance. Our Phase I effort showed that it is possible to passivate dislocations with the introduction of hydrogen atoms using a high density plasma source. Specifically, we found that hydrogen increases carrier recombination lifetimes and mobilities through the passivation of dislocations. In this proposed Phase II effort, we will employ the hydrogen passivation technique to improve the performance of LWIR HgCdTe single-element planar and mesa photodiodes on Si substrates. We will also fabricate and test large area focal plane arrays that have hydrogen-passivated HgCdTe as the active material.