High-Performance Germanium P-I-N Photodiodes for High-Speed, Hard X-Ray Imaging

Design, fabrication, and measurement of vertical Germanium (Ge) Photodiodes for high-speed, hard X-Ray imaging is presented. The devices used atmospheric-pressure epitaxial absorption layers, varying absorption layer thicknesses (10 – 245 μ m) over bulk-Ge substrates, fabricated in various sizes. Measurements include large-signal and transient-response from X-ray source between 6 keV and 28 keV. The results approach a 100% external quantum efficiency with 245 lm absorption regions and a 22% improvement in temporal response with 10μ m absorption region compared to an Si reference device of the same active area.. Authors: Guo, Ziang [University of California, Davis, CA (United States); University of Illinois at Urbana-Champaign, IL (United States)] (ORCID:0009000751301814); Mistyuk, Sergei [University of California, Davis, CA (United States); Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)]; Carpenter, Arthur [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)]; Hunt, Charles E. [University of California, Davis, CA (United States)]. DOE Contract: AC52-07NA27344. Subjects: 47 OTHER INSTRUMENTATION; Absorption; Engineering; Epitaxial layers; Germanium; Imaging; Lasers; Optical detectors; Optical sensors; P-I-N diodes; Photodiodes; Photonics; Silicon; Spatial resolution; Testing