New Sensing Capabilities for Space Situational Awareness

This proposal addresses “New Sensing Capabilities for Space Situational Awareness" and describes a revolutionary approach for developing large field-of-view, high-sensitivity VLWIR sensors to detect and track space objects. Our revolutionary approach is to develop a new junction architecture, the lateral-collection planar micro-junction based on single-layer Liquid Phased Epitaxy (LPE), that is more tolerant of defects and that eliminates interfaces and process steps where contamination and defects can be introduced. This new technology will be compatible with usual silicon Read Out Integrated Circuits (ROICs) for back illuminated Focal Plane Arrays (FPAs). The proposed planar lateral-collection micro-junction is a new junction architecture for HgCdTe that has important benefits over traditional two-layer LPE mesa structure, which should lead to improved operability and array yield. Because it is a planar architecture, the thickness and quality of the critical CdTe passivation layer is more controllable and reproducible. Small-area unit cells, below 20x20 µm², are facilitated. Operability and yield should both be improved because the new fabrication process is much simpler. The mesa etch step is eliminated, and there is no need for LPE growth of a second HgCdTe layer. Photolithography on planar surfaces is also easier. Supporting Photronix in this effort is BAE SYSTEMS.