Wide bandgap semiconductor radiation detectors for future space applications

SiC and Al0.52In0.48P photodiodes were experimentally investigated for their suitability as radiation detectors for use in high temperature (= 20 °C) environments applications. Commercial-off-the-shelf (COTS) 4H-SiC UV p-n photodiodes were repurposed for use as X-ray detectors. Custom-made Al0.52In0.48P p+-i-n+ mesa X-ray photodiodes were also studied. The measurements used an 55Fe radioisotope X-ray source. The electrical characterisation of the commercial 4H-SiC UV p-n photodiodes and the Al0.52In0.48P p+-i-n+ mesa X-ray photodiodes were investigated at temperatures up to 140 °C and 100 °C, respectively. The photocurrent of the commercial 4H-SiC UV p-n photodiodes were also investigated at temperatures up to 80 °C. The temperature dependences of the energy resolution (FWHM at 5.9 keV) of photon counting spectrometers employing these two different kinds of photodiodes are reported, along with shaping time noise analysis. One of the commercial 4H-SiC UV p-n photodiodes was subsequently characterised under illumination from X-rays of energy 4.95 keV to 21.17 keV, generated by fluorescing high purity metal foils with X-rays from a Mo target X-ray tube. These measurements were conducted at a temperature of 33 °C. The investigation included measurements of spectrometer energy resolution, energy response linearity, and flux linearity measurements. One of the commercial 4H-SiC UV p-n photodiodes was further studied as a direct electron detector of soft (< 66 keV) electrons (ß- particles) at temperatures up to 100 °C. In addition to experimental measurements, Monte Carlo simulations were conducted and compared with the spectrometer’s response. Results of the research presented in this thesis indicates the commercial 4H-SiC UV photodiodes and the Al0.52In0.48P X-ray photodiodes can be used for high temperature X-rays spectroscopy. Moreover, the results also show that the commercial 4H-SiC UV photodiode can be used for high temperature electron spectroscopy. The work with the 4H-SiC UV photodiodes shows that they can be repurposed for use in low cost X-ray spectroscopy missions, such as CubeSat instrumentation to monitor solar X-rays. The work with the Al0.52In0.48P X-ray photodiodes shows the current state of the art of custom compound semiconductor X-ray detectors specifically designed for such environments.