Field Programmable Short Wave Infrared Photodetectors

We propose to advance the state-of-the-art in short wave infrared (SWIR) detectors to meet NASA’s needs for advancements in communications technology. Antimonide-based Type II Superlattice (T2SL) infrared (IR) detectors have made significant advances in the past decade. The interest in this technology stems from (1) the ability to tailor the T2SL bandgaps across the IR region and (2) the manufacturability of T2SL structures using III-V foundries and horizontal integration schemes. NASA researchers have been involved with efforts to develop T2SL IR detectors for a variety of space-related missions, both in communications and sensing. We propose to complete a fundamental feasibility study leading to a prototype of a single pixel, field programmable, SWIR photodetector. This detector will use antimonide-based T2SL materials as the absorber. This detector will operate at relative high temperature (above 250K). Most uniquely, this detector’s voltage bias can be programmed to operate with either high dynamic range or high sensitivity. High dynamic range uses a low voltage bias (<1V) and operates the detector in a standard PIN configuration. High sensitivity uses a high voltage bias (20 to 30V) and operates in the linear amplification region of an avalanche photodiode (APD). The detector is engineered for high signal-to-noise operation in both modes. The user or the control software can adaptively trade off dynamic range versus sensitivity on the fly and in response to measured characteristics of the scene (for example, photon flux or noise conditions). This detector will work ideally with an emerging generation of readout integrated circuits that will control the voltage of pixels selectively, leading to a focal plane array (FPA) that can algorithmically decide the operational mode of each pixel. Because the band structure of T2SL materials is designed, we will be able to engineer a detector that meets all of these targets simultaneously.