ALD Passivation of SLS Detectors

Pixel sidewalls of antimony-based type-II strained layer superlattices (SLS) with infrared energy bandgaps have electron accumulation (in n-type SLS) or electron inversion (in p-type SLS) surface layers that contribute leakage current that affects detector performance. These conductive surfaces are a consequence of surface Fermi level pinning in these materials and have to be prevented to address the leakage problem. Atomic Layer Deposition (ALD) is a promising approach to such passivation, especially given its ability to conformally coat the deep trenches that need to be etched between short-pitch pixels and dualband pixels. In Phase I, we will experimentally investigate ALD passivation in combination with different surface treatments. In the Phase I Option, we will evaluate the passivation technique on p-doped absorbers - a much harder problem. Phase II will focus on further process refinements and the realization of megapixel small-pitch dualband focal plane arrays with low dark current.