Hard X-ray and γ-ray spectroscopy at high temperatures using a COTS SiC photodiode

Abstract

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...

Mo/4H-SiC Schottky diodes for room temperature X-ray and γ-ray spectroscopy

“…The energy resolution achieved with the Mo/4H-SiC Schottky diode detector spectrometer is similar to that achieved with other previously reported 4H-SiC detector spectrometers, employing similar preamplifier electronics. Notable examples include: a FWHM at 22 keV of 1.47 keV at 23 °C achieved with an early semi-transparent NiSi/4H-SiC Schottky diode [10]; a FWHM at 5.9 keV of 1.5 keV at 20 °C achieved with another generation of NiSi/4H-SiC Schottky diode detector [11]; a FWHM at 17.4 keV of 1.36 keV at 30 °C which was achieved with another type of NiSi/4H-SiC Schottky diode [12]; a FWHM at 5.9 keV of 1.26 keV at 20 °C achieved with a recent Ni2Si/4H-SiC Schottky diode [13]; and a FWHM at 5.9 keV of 1.66 keV ± 0.15 keV at 20 °C achieved with a commercial UV 4H-SiC p-n photodiode repurposed for X-ray detection [15]. However, all of these energy resolutions are substantially poorer than was achieved with a Au/4H-SiC Schottky diode and exceptionally low-noise preamplifier electronics (3 erms ENC, when unloaded, at room temperature): with this detector, a FWHM at 5.9 keV of 196 eV at 30 °C was reported [9].…”

Investigation of Ni/Y2O3/n-4H-SiC metal-oxide-semiconductor structure for high-resolution radiation detection

“…Due to its high thermal conductivity (4.9 W/cm/K), average displacement threshold (22-35 eV), and wide energy bandgap of the polytype 4H-SiC (3.27 eV), 4H-SiC-based electronic devices are appropriate for harsh environment applications such as high-radiation environments and high-temperature applications [3] [4] [5] [6] [7] [8] [9]. Metal-on-4H-SiC Schottky barrier detectors (SBDs) with epitaxial layer thicknesses of tens of micrometers are common choices for detection of x-rays and charged particles like alpha particles [10] [11] [12] [13] [14] [15] [16]. To detect and collect the irradiation induced charge carriers in 4H-SiC efficiently, an electric field of appropriate strength must be maintained within the detector material to form a depletion region and to collect the electron-hole pairs.…”

Electrical Characterization of 6H-SiC/MEH-PPV/Al Schottky Diode by Current-Voltage Method in A Wide Temperature Range

“…Due to its indirect band structure, its optical properties are also prominent, so there are photovoltaic studies on this material (Sciuto et al, 2017). Apart from these, SiC, which has a wide range of uses from various sensors to detectors, continues to be the focus of many researches (Bernat et al, 2021;Bodie, Lioliou, & Barnett, 2021;Zaťko et al, 2021). Determining the electronic parameters of SiC, which has such a wide application area, is very valuable.…”