SBIR Phase I: High Efficiency, Wide-Bandgap Photocathodes for Solar-Blind UV Photon Counting and Imaging

该小型企业创新研究（SBIR）第一阶段项目旨在开发基于宽带隙III族氮化物半导体的创新高效紫外光电阴极。基于Al_xGa_（1-x）N合金的光电阴极具有3.4 - 6.2 eV的带隙（对于Al组分x从0到1），可以填充碱金属卤化物光电阴极（λ 200 nm）与包括多碱金属和GaAs的各种光学光电阴极（λ 400 nm）之间的150-400 nm范围内的差距。除了高性能UV图像传感器之外，这些结构还被考虑用于无掩模电子光刻和固态照明中的高亮度电子发射器。该项目将把这些高效率的紫外光探测器与增强器结合起来，以制造高分辨率和高灵敏度的日盲紫外光传感器，用于光子计数和成像应用。请注意，III族氮化物材料的化学和热稳定性以及抗辐射性使这些探测器适用于恶劣环境中的应用。未来仪器的要求对阴极开发提出了新的挑战，特别是在生产高效和稳定的光电阴极方面。主要改进包括更高的检测效率、更好的辐射和表面曝光稳定性以及更强的带通外光抑制。（λ 400 nm）具有广泛的应用，包括商业和军事，特别是在需要在存在大的可见光和/或红外（IR）背景的情况下分析光的UV分量的那些区域中。采用分子束外延技术生长出高质量的光电阴极，这意味着它们可以在大直径衬底上生长，并且性能均匀。大幅面紫外图像传感器在空间科学和军事应用中有着巨大的需求。该计划中高效“无铯”光电阴极的开发将为上述应用提供多功能、更可靠和更低成本的紫外传感器。最后，本计画所发展的技术，可应用于量测与无罩幕电子微影技术中，以制造高亮度电子发射器。

This Small Business Innovation Research (SBIR) Phase I project is directed toward the development of innovative high-efficiency UV photocathodes based on the wide bandgap III-nitride semiconductors. Photocathodes based on AlxGa1-xN alloy with a bandgap of 3.4 to 6.2 eV (for Al composition x from 0 to 1) can fill the gap in the 150-400 nm range between alkali halide photocathodes (lambda 200nm) and various optical photocathodes including multialkali and GaAs (lambda 400nm). In addition to high-performance UV image sensors, these structures are considered for high-brightness electron emitters in maskless electron lithography and solid-sate lighting. This project will integrate these high-efficiency UV photodetectors with intensifiers to fabricate high resolution and high sensitivity solar-blind UV sensors for photon-counting and imaging applications. Note that the chemical and thermal stability and radiation hardness of III-nitride materials make these detectors suitable for applications in harsh environments. The requirements of future instruments pose new challenges for cathode development, particularly in the production of highly efficient and stable photocathodes. The key improvements include higher detection efficiency, better stability under radiation and surface exposure, and stronger out-of-bandpass light rejection.Detection of light in the ultraviolet (UV) range (lambda 400 nm) has a wide range of applications, both commercial and military, particularly in those areas where the UV component of light needs to be analyzed in the presence of large visible and/or infrared (IR) backgrounds. High-quality photocathodes were grown by MBE technique, which means that they can be developed on large diameter substrates with uniform performance. Large-format UV image sensors are in great demand for space science and military application. The development of high-efficiency 'cesium-free" photocathodes in this program will result in versatile, more reliable and lower cost UV sensors for the applications mentioned above. Finally, the technology to be developed in this program can results in high-brightness electron emitters for applications in metrology and maskless electron lithography.