High Operability HgCdTe Focal Plane Arrays on Si by Mitigation of Defects

For HgCdTe infrared focal plane arrays fabricated on Si substrates, a model has recently been proposed to account for the disparity between the density of failed pixels and the density of dislocations that are present in the HgCdTe junction region. The model distinguishes between active and inactive dislocations and offers a hypothesis that dislocations are active only when they intersect particulates in the region near the Si wafer surface. We propose to test the validity of this hypothesis by separating the regions of high particulate density from regions of high dislocation density by depositing a homoepitaxial layer of Si. The particulates that lie at the surface of the Si wafer will not be able to interact with the dislocations that lie of the plane of the interface between Si layer and ZnTe buffer layer. We anticipate a low density of active dislocations in the HgCdTe and a low density of failed pixels in Si-based HgCdTe focal plane arrays. Operability values for these arrays should then meet systems"requirements.