Evaluation of COTS silicon carbide photodiodes for a radiation-hard, low-energy x-ray spectrometer

Wide band-gap semiconducting materials such as silicon carbide (SiC) are attractive alternatives for radiation detection in more rugged environments due to low leakage currents, superior radiation hardness, and temperature insensitivity. However, the development of these technologies has been hindered by serious materials problems that restrict the quality and size of detector grade crystals. Recent developments in epitaxial growth of thin crystals on a substrate are yielding detector-grade material of reasonable dimension. While applications for ionizing radiation detectors are still limited primarily to small academic and R&D ventures, an active market exists for very thin epitaxial SiC photodiodes for the purpose of detecting UV light in high-temperature environments. The purpose of this project is to evaluate the utility of these commercially available SiC UV photodiodes for the purpose of detection and measurement of low-energy x-rays. We present results from bench-top electronic characterization, radioactive source measurements, x-ray source measurements at Los Alamos National Lab, and responsivity measurements performed at the National Synchrotron Light Source at Brookhaven National Lab.