Monolithic integration of high-efficiency III-nitride photocathodes and microchannel plates using a novel metallic contact

Detection of light in the ultraviolet (UV) range (100nm to 400 nm) has a wide range of commercial, scientific and military applications, particularly in those areas where the UV component of light needs to be analyzed in the presence of a large amount of visible and/or infrared (IR) background light. nbsp;High-performance photodetectors and imagers are essential parts of the enabling technology for future space-borne astronomy. nbsp;Sensitivity, spatial and temporal resolution, photometric accuracy, and reliability of these photodetectors will be critical when defining, planning, and exploiting future space missions. In particular, for UV spectroscopy and low-light-level UV-imaging applications, there are strong demands for improved detectors which have higher quantum efficiency (QE), lower dark current, and more stable and robust operation. Highly robust, wide-bandgap gallium-nitride (GaN), and its alloys with aluminum and/or indium, are the most promising semiconductors for development of UV photodetectors for applications in space-based UV spectroscopy and imaging. nbsp;In the Phase I program, Qrona Technologies, in collaboration with the space Science Laboratory at UC Berkeley, will develop and fabricate high-efficiency and high-resolution UV phototubes by depositing high-quality GaN-based photocathode structures directly on microchannel plates (MCPs), using a novel lattice-matched metallic buffer/contact layer. nbsp;Monolithically integrated semiconductor photocathode/MCP detectors cannbsp;achieve potentially much higher-performance than conventional phototubes in many applications, including higher detection efficiency, improved spatial and temporal resolutions, more immunity to magnetic fields, and better photoresponse uniformity on large format imagers, as well as reducing the device weight, size, complexity, and fabrication cost.