Reduction of surface leakage for high performance LWIR T2SL FPAs

High performance infrared detectors in the LWIR regime are highly needed in a number of missile defense missions. In order to image targets from long distance, it is important that imagers have high sensitivity and high resolution. This leads to technical goals of having low noise, low dark current in small size pixels in large arrays. While saturated performance levels of traditional systems based on bulk semiconductors have not quite met the requirement of applications, it is expected that novel quantum systems will bring new development stage for infrared imagers. In recent years, Type-II InAs/GaSb superlattice (T2SL) has experienced significant development, from theoretical modeling, material growth to device processing and packaging. Performance of LWIR detector based on T2SL has become comparable, even better than that of HgCdTe. However, LWIR T2SL devices have been shown to be limited by surface leakage, especially at lower operating temperature. This proposed effort will address surface processes in order to suppress this bottle neck of T2SL technology. By correlating the influence of structural design and material quality on surface leakage and by utilizing the best etching, cleaning and passivation techniques, a high performance LWIR FPA with dark current below 1uA/cm2 at 67K will be demonstrated.