Dark current plays an essential role in the performance of LWIR InAs/GaSb SL-based FPAs. Previous improvements in material quality and device design have significantly suppressed bulk contributions to the dark current. The dark current due to surface defects becomes prominent with decreasing detector size, as in the case of high-resolution FPAs. Furthermore, for LWIR FPA with very small band gap energies, a small change in the Fermi level, due to the formation of defects on sidewalls during device fabrication, may cause majority carrier inversion near the sidewall resulting in diode shunts. Therefore, improving the passivation is of particular importance to FPA performance. Spire Semiconductor proposes to make InAs/GaSb SL based LWIR FPAs with low surface leakage current using a unique processing and passivation techniques developed in Spire Semiconductor. In phase I, Spire Semiconductor targets small array (64x64, pixel size ~~25x25 mm-2) with a bulk-limited R0A product and sidewall surface resistivity higher than 10KW cm at an operation temperature of 77K. In Phase II, Spire Semiconductor will work with FLIR to develop high definition 1k x 1k FPAs for Space applications.
Keywords: Inas/Gasb, Long Wavelength Infrared, Photodetector, Focal Plane Array, Surface Passivation
