Low-Cost, Uncooled, NIR and SWIR FPA Using SiGeSn on Silicon

The U.S. Army has identified germanium tin (Ge1-ySny) materials as a promising enabling technology for near infrared (NIR) and short-wave infrared (SWIR) uncooled focal plane array (FPA) applications. Such applications involve night vision in challenging conditions (e.g. overcast starlight), in addition to target illumination and advanced light detection and ranging (LIDAR). Currently utilized image intensifier (I2) and thermal goggle technology for man-portable applications, such as the AN/PSQ-20 Enhanced Night Vision Goggle (EVNG) and ENVG-B, are bulky in size and weight and do not lend themselves to be fused with a wide array of other solid-state sensors at SWIR and MWIR wavelengths. While conventional NIR and SWIR III-V (e.g. gallium indium antimonide, or GaInSb) and II-VI (mercury cadmium telluride, or HgCdTe) semiconductor materials show improvements in performance, their high-cost and material incompatibility make them prohibitive for monolithic integration into low-cost Si CMOS processes for further reductions in cost, size, weight and consumed power (C-SWaP). Additionally, conventional silicon Charge Coupled Devices (CCDs) and Complementary Metal Oxide Semiconductor (CMOS) imagers have not demonstrated passive low light imaging under overcast starlight levels, in particular at SWIR wavelengths. The development of Ge1-ySny alloy materials that can be monolithically integrated with a CMOS based read-out integrated circuit (ROIC), would provide significant reductions in C-SWaP while simultaneously enhancing the Army’s Soldier Lethality modernization priority. Freedom Photonics and Arizona State University propose to further the development of GeSn detector technology through a parallel path of two different detector architectures within the GeSiSn materials system. Using these Group IV materials leverages Si CMOS technology, allowing for significantly lower processing and materials cost compared to III-V materials. Furthermore, developing detector arrays in the GeSiSn materials systems allows the bandgap of the material to be tailored to meet needs from near infrared to longwave infrared wavelengths. Because of this, GeSiSn material FPAs have applications not only in challenging night vision conditions, but also in other Intelligence, Surveillance, and Reconnaissance (ISR) systems. The key technical objective of this proposal is the development of low-cost, uncooled NIR and SWIR FPAs using the GeSiSn materials system.