4H-Sic and Novel SI GaAs-based M-S-M Radiation Hard Photodetectors Applicable in UV, EUV, and Soft X-Ray Detection: Design, Technology, and Performance Testing

Work reports on results in development of 4H-SiC and semi-insulating (SI) GaAs large area surface barrier detectors. 4H-SiC detectors are based on high purity liquid phase epitaxy layer with the Schottky barrier contact formed by semitransparent Ni. SI GaAs detectors are based on bulk undoped material using novel electrode metallization with improved sensitivity in UV and soft X-ray ranges. The novel detector use semitransparent low work function Mg metal contact giving a new electronic characteristic of the junction. Electrical characteristics of the diodes, photocurrent measurements and pulse height spectra of gamma and low energy X-rays using the Am-241 source, are presented. Improvement of 4H-SiC detector resistance to gamma radiation and neutron fluency is demonstrated. Problems with design and application of related ultra-low noise electronics are introduced and discussed.