Multi-spectral Infrared Photodetectors and Focal Plane Arrays based on Band-engineered Type-II Indium-Arsenic / Gallium-Antimony Superlattices and its Variants

Type-II InAs/GaSb superlattices (T2SLs) is a quantum system that has recently garnered much attention for high performance infrared applications. Superlattices can be considered as an artificial bulk material with alternating heterojunctions at the atomic scale where electrons and holes are spatially separated into the InAs and GaSb wells respectively. The effective bandgaps are tailorable from 40meV to 400meV, making it highly suitable for imaging multiple wavebands in the infrared. With a high electron effective mass and energy bands that can also be optimized for the suppression of Auger recombination, T2SLs has drawn considerable interest in recent years and proves to be a prime candidate for third generation imaging.;The general principles presented here are powerful and illustrate the flexibility of the T2SL system. The trends seen in the LWIR have also been applied to the MWIR regime resulting in impressive electrical performances at high operating temperatures. Combined with high quantum efficiencies typical of the T2SL material system, both the MWIR and LWIR detectors have reached 300K background-limited performances as demonstrated in this work.;The bulk material improvements witnessed, however, make the manufacturability of the T2SL system more challenging, particularly in the aspect of mesa delineation. As the bulk material resistance is elevated, the delineated surface can become the path of least resistance and the result can be detrimental as semiconductor surfaces have been known to be a source of excess noise that could ultimately limit the detector's signal resolution. The difficulty of the problem is compounded by the fact that plasma etched diodes, where high energy ions are driven by an electric field toward the semiconductor to create anisotropic profiles, have been empirically evidenced to generate surface traps. Inductively coupled plasma etching techniques have been investigated in this work. This investigation found that the superlattice designs used in LWIR detectors were more "resistant" to the surface traps generated from the optimized ICP etching developed, than higher bandgap superlattices from the SWIR to the MWIR. Empirical evidence suggests that such a phenomenon could be explained through relative surface trap positions to the Fermi level, as well as to the conduction and valence band-edges of the designed superlattice.;From an optical standpoint, high quantum efficiencies demand thick active regions and therefore high aspect ratio trenches to be defined in the semiconductor in order to preserve the optical detector volume or fill factor. Etched trenches as deep as 12µm and roughly 3µm in width have been demonstrated. These achievements provide the foundation for focal plane array development, especially for multi-spectral detectors where multiple p-n junctions are stacked together.;Understanding how to etch the superlattice pixel has enabled a wide variety of hybrid IR FPAs to be demonstrated. Prior to multi-color camera development, single color cameras were first evaluated in the MWIR and LWIR. Background limited performances were achieved in both wavelength regimes with temperature sensitivities as low as 9mK (MWIR F...