Development of Antimonide Based Avalanche Photodiodes for SWIR Remote Sensing Applications.

There is growing interest in the design, development, and demonstration of short wavelength infrared (SWIR) avalanche photodiodes (APDs), notably focusing on spectral coverage over 1.55-2 µm in wavelength. This work investigates GaAsSb/AlGaAsSb APDs on InP substrates for these remote sensing applications. The objective is to develop infrared detectors that will meet or exceed the opto-electronic performance metrics of state-of-the-art technology while operating at high temperatures (>200 K) to reduce SWaP-C and ultimately enable integration of the technology onto small satellite platforms. While our GaAsSb/AlGaAsSb SACM APDs exhibit promising performance, there are several challenges that need to be overcome before their implementation into fieldable remote sensing systems. Chiefly, the detectors exhibit high dark current relative to competing commercial detectors. The dark current must be identified as bulk or surface dominated through careful characterization and analysis. If it is determined that the dominant dark current mechanism is bulk driven, improvements in the APDs will result by improving the material quality through crystal growth optimization. If the APDs are surface dark current limited, then improvements will occur by reassessing the fabrication techniques. Through this, we can further adjust our design, growth, and fabrication processes to achieve high performing SWIR infrared detectors.