GeSiSn Avalanche Photodiode Arrays for High-Sensitivity SWIR Imaging Applications

The germanium silicon tin (GeSiSn) materials system has been identified as a promising enabling technology for critical short-wave infrared applications. In particular, the GeSiSn materials system offers a unique design space for avalanche photodiodes, which offer sgnficantly enhanced sensitivint over conventional PIN structures, with applications in next-generation Intelligence, Surveillance, and Reconnaissance (ISR) systems, night vision, and Light Detection and Ranging (LiDAR). Currently, a major technology gap exists for small-pitch, large format detector arrays capable of operating at a wavelength of 2 µm or longer, without the need for physically sizable cooling, which can be addressed using a GeSiSn APD. Freedom Photonics has significant technology experience focused on the development of PIN photodiodes using this materials system, including arrayed devices. In Phase II of this SBIR program, Freedom Photonics will develop single element avalanche photodiodes using GeSiSn materials suitable for operation at a SWIR wavelengths out to 3 µm. This effort will include the design, fabrication, and characterization of the first generation of these avalanche photodiodes, demonstrating the feasibility assessed in the Phase I. The overall objective of this program is to develop APD arrays for integration into focal plane arrays.