Nanostructures for dislocation blocking in infrared detectors: Dislocation Reduction In Infrared Detector Materials Grown on Si Substrates Using Nan

Large format, low cost, reliable and high performance infrared focal plane arrays are essential for the Army’s Third Generation IR Imaging Technology. HgCdTe (MCT) detectors fabricated on silicon substrates are an attractive alternative generating considerable interest. State of the art technology produces CdTe buffer and MCT epitaxial layers with dislocation densities of 5x105 and 106-107/cm2 respectively on silicon substrates. In Phase I we investigated the use of a CdTe nanocrystalline buffer layer to reduce the dislocation density. The presence or the incomplete removal of SiO2 on the substrate surface posed severe problems in achieving dislocation density reduction. To overcome this problem we will use germanium coated silicon and patterned Ge/Si substrates since GeOx is much more volatile than SiOx. These substrates will be spin-coated with CdTe nanocrystals (by low cost colloidal synthesis) followed by heat treatment and epitaxial over layer growth of CdTe and MCT layers. The result will be CdTe/Ge/Si compliant substrates having dislocation density of 105/cm2 or less. These substrates will be used for the deposition of MCT device layers and fabrication of IR detectors. High quality CdTe/Ge/Si compliant substrates with low dislocation density, device quality MCT layers and fabricated MCT-IR detectors will be provided to ARL.