PbSnTe Thermoelectric Cooled Focal Plane Arrays on Novel Silicon Based Substrates

The MDA's request to detect, track and discriminate long range targets requires infrared focal plane arrays (IRFPAs) that have higher sensitivities, longer cutoff wavelengths (>14 µm), larger formats (> 256 x 256), and higher operating temperatures than the current infrared technology. PbSnTe is an ideal material for the MDA's requirements. Its carrier mobilities and quantum efficiencies are comparable or even higher than HgCdTe in the mid (3-6 µm) and far (6-14 µm) infrared. In addition, it has been reported that PbSnTe heterojunction detectors have the ability to operate at room temperature. However, viable solutions still need to be found to alleviate the materials obdurate elastic problems. In Phase I, EPIR Technologies will epitaxially grow PbSnTe on silicon with a CdTe/ZnTe buffer layer. This buffer will partially alleviate the lattice mismatch and provide superior adherence to the substrate. The silicon substrate does not suffer from the instability of the typically used CaF2 and BaF2 buffers and will allow for easy integration into existing IRFPA technologies. EPIR Technologies will then demonstrate high temperature operation of single element detectors. In Phase II, EPIR Technologies will address thermal mismatch issues though compliant technologies.