A commercial-off-the-shelf (COTS) silicon carbide (4H-SiC) UV photodiode was electrically characterized and investigated as a low-cost spectroscopic photon counting detector of X-rays and γ-rays. The detector was coupled to a custom-built low-noise charge-sensitive preamplifier, and illuminated by 55 Fe and 109 Cd radioisotope X-ray sources and an 241 Am radioisotope γ-ray source, thus providing photon energies from 5.9 keV to 59.5 keV. The detector and preamplifier were operated uncooled at temperatures between 20 °C and 100 °C. The energy resolution (full width at half maximum, FWHM) of the spectrometer was found to be 1.66 keV ± 0.15 keV at 5.9 keV and 22.16 keV, and 1.83 keV ± 0.15 keV at 59.5 keV when operated at 20 °C. At a temperature of 100 °C, the FWHM were 2.69 ± 0.25 keV, 2.65 keV± 0.25 keV, and 3.30 keV ± 0.30 keV, at the same energies. Shaping time noise analysis found dielectric noise to be the dominant noise source, except when long amplifier shaping times were used at high temperatures when white parallel noise dominated. Noise associated with incomplete charge collection was found to be negligible at energies up to 22.16 keV and at temperatures ≤ 60 °C; but incomplete charge collection noise could not be discounted when the spectrometer was operated at higher temperature (80 °C) and at higher energy (59.5 keV). Although the detector was thin (and thus inefficient at high photon energies) the low cost and commercial availability of the SiC device make it an attractive prospect for use in cost-sensitive applications such as university-led CubeSat missions. IntroductionMany semiconductor materials have been investigated for use as photodiodes for photon counting X-ray spectrometers. However, Si with its bandgap, Eg, of 1.12 eV [1], remains the gold standard spectroscopic X-ray photodiode material for use at relatively cool temperatures (≤ 20 °C) [2]. Because of its relatively narrow bandgap, Si radiation detectors typically require cooling to limit the thermally generated leakage current that can degrade the energy resolution of an X-ray spectrometer [3]. Radiation shielding is another common prerequisite for spectroscopic Si detectors sited in environments of high energy radiation, e.g. space [4]; radiation damage to Si detectors can be sufficient to cause substantial degradation in performance, even in the relatively benign Earth-Moon environment [5]. As such, significant research attention has been paid to developing alternative semiconductor materials for photon counting radiation spectroscopy, particularly with future space science applications in mind. GaAs [6] (Eg = 1.42 eV [7]), CdZnTe [8] (Eg = 1.54 eV [9]), Al0.8Ga0.2As [10](Eg = 2.09 eV [11]), 4H-SiC [12] (Eg = 3.27 eV [13]), and Diamond (Eg = 5.47 eV [14,15]), are among many wide bandgap semiconductors that are considered to be intrinsically more radiation tolerant than Si in most circumstances, and with the exception of diamond, these materials have been shown to be capable of spectroscopic X-ray response at elevated temperatures (≥ 20...

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An electronic grade single crystal chemical vapour deposition diamond was investigated as a prototype high temperature spectroscopic electron (β− particle) detector for future space science instruments. The diamond detector was coupled to a custom-built charge-sensitive preamplifier of low noise. A 63Ni radioisotope source (endpoint energy 66 keV) was used to provide a spectrum of β− particles incident on the detector. The operating temperature of the detector/preamplifier assembly was controlled to allow its performance to be investigated between + 100°C and − 20°C, in 20°C steps. Monte Carlo modelling was used to: a) calculate the β− particle spectrum incident on the detector; b) calculate the fraction of β− particle energy deposited into the detector; and c) predict the β− particle spectrum accumulated by the instrument. Comparison between the model and experimental data suggested that there was a 4.5 µm thick recombination region at the front of the detector. The spectrometer was demonstrated to be fully operable at temperatures, T, -20°C ≤ T ≤ 80°C; the results suggested that some form of polarisation phenomenon occurred in the detector at > 80°C. This article presents the first report of a calibrated low energy (⪅ 50 keV) spectroscopic β− particle diamond detector.