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-氮化物半导体的创新高效紫外光阴极。Al_xGa_(1-x)N合金的带隙为3.4~6.2 eV(Al组分x从0到1)的光电阴极可以填补碱金属卤化物光电阴极(波长200 nm)与包括多碱和砷化镓(波长400 nm)在内的各种光学光电阴极之间的空隙。除了高性能的UV图像传感器外，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集成在一起，以制造用于光子计数和成像应用的高分辨率和高灵敏度的日盲紫外光传感器。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用于恶劣环境中的应用。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。主要的改进包括更高的检测效率，在辐射和表面曝光下更好的稳定性，以及更强的带外光抑制。在紫外线(UV)范围内(波长400 nm)的光检测具有广泛的应用，无论是商业还是军事，特别是在那些需要在大的可见光和/或红外(IR)背景下分析光的UV成分的领域。用分子束外延技术生长出了高质量的光电阴极，这意味着可以在大直径的衬底上生长出性能均匀的光电阴极。空间科学和军事应用对大面阵紫外光图像传感器的需求很大。该计划中开发的高效无铯光电阴极将为上述应用带来多功能、更可靠和更低成本的紫外光传感器。最后，该计划中开发的技术可以产生用于计量和无掩模电子光刻应用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.