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

Mo/4H-SiC Schottky diodes were investigated as detectors for their suitability in photon counting X-ray and γ-ray spectroscopy. The Schottky diodes, with a 35μm thick n− epitaxial layer, were treated with a phosphorus pentoxide surface passivation, which had been previously shown to improve the homogeneity of the metal–semiconductor interface and suppress leakage current. One device was coupled to a low-noise charge sensitive preamplifier and standard onwards readout electronics; the resultant spectrometer was used to accumulated X-ray and γ-ray spectra. The spectrometer had an energy resolution of 1.67 keV ± 0.08 keV (97 e− rms ± 5 e− rms) at 5.9 keV and 1.6 keV ± 0.1 keV (93 e− rms ± 6 e− rms) at 59.54 keV. Despite the moderate energy resolution achieved, the results suggested that the leakage current of the Mo/4H-SiC Schottky diode detector was not the dominant source of noise limiting the energy resolution of the spectrometer at the optimum operating conditions at room temperature; lossy dielectrics in close proximity to the input of the preamplifier (including stray dielectrics) and the relatively large average electron–hole pair creation energy of 4H-SiC (an inherent property) were the main contributors to the achieved energy resolution in energy terms.