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

这项小型企业创新研究（SBIR）一期项目旨在开发基于宽带隙iii型氮化物半导体的创新型高效紫外光电阴极。AlxGa1-xN合金光电阴极的禁带宽度为3.4 ~ 6.2 eV（对于Al成分x为0 ~ 1），可以填补碱卤化物光电阴极（λ 200nm）和多碱GaAs光电阴极（λ 400nm）在150 ~ 400nm范围内的空白。除了高性能紫外图像传感器外，这些结构还被认为是无掩模电子光刻和固体安全照明中的高亮度电子发射器。该项目将集成这些高效紫外光电探测器和增强器，制造高分辨率和高灵敏度的太阳盲紫外传感器，用于光子计数和成像应用。请注意，iii -氮化物材料的化学和热稳定性以及辐射硬度使这些探测器适合在恶劣环境中应用。未来仪器的要求对阴极的发展提出了新的挑战，特别是在生产高效和稳定的光电阴极方面。关键的改进包括更高的检测效率，更好的辐射和表面暴露稳定性，以及更强的带外通光抑制。紫外（UV）范围内的光检测（λ 400 nm）具有广泛的应用，包括商业和军事，特别是在需要在大可见和/或红外（IR）背景下分析光的紫外成分的领域。采用MBE技术制备了高质量的光电阴极，这意味着它们可以在大直径的衬底上生长，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。该项目中高效“无铯”光电阴极的开发将为上述应用带来多功能、更可靠和更低成本的紫外线传感器。最后，在这个程序中开发的技术可以产生用于计量和无掩模电子光刻的高亮度电子发射器。

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.