CMOS Compatible SWIR-Response Silicon Detectors

ABSTRACT: CMOS silicon imagers are the dominant focal plane arrays for visible light imaging. Over several decades, there have been investigations in broad near-infrared (NIR) spectral response using laser doped and structuring silicon (Si) detectors, including so-called"black"silicon imagers. But, to date the data shows that the fs-laser ablation and subsequent resolidification of the"black"silicon surface results in significant dark current and unstable spectral response. In Phase I, it will be shown that extrinsic chalcogen doping of the surface of silicon microtips can be achieved using PbS nanocrystal layers electronically bound to the bandgap of the silicon by inorganic ligands. Extended short-wavelength-infrared (SWIR) response, low dark current, high detectivity, high charge injection, and low image lag can be achieved using extrinsic PbS nanocrystal sensitization layers on CMOS compatible substrates. In Phase I a series of varying diameter photodetectors and small sized arrays will be fabricated and demonstrated. In Phase II, fully-function, large format SWIR imagers will be built using facile, CMOS compatible processes. BENEFIT: The most recent developments in target tracking, target identification, and high-speed free-space communication involve the shortwave-infrared (SWIR) region of the electromagnetic spectrum. Lasers at SWIR wavelengths can be eye-safe at high power and propagate more efficiently through the atmosphere than visible lasers. These laser emissions are undetectable to most imaging technologies, including silicon, CCD cameras, night-vision tubes, and long-wave IR cameras. SWIR applications include seeing battlefield lasers, facial recognition, battle damage assessment, seeing-through-dust, pilot vision enhancement, laser-aided spotting scope, active passive rangefinders, celestial navigation.