High-Resolution Alpha Spectrometry Using 4H-SiC Detectors: A Review of the State-of-the-Art

Silicon Carbide (SiC) semiconductor radiation detectors were first demonstrated in 1957, however, meaningful progress was delayed until the mid-1990s when high-quality epitaxially-grown SiC became available. Rapid progress ensued, and the detection of alpha particles, gamma and X-rays, protons, fission fragments, heavy ions, beta particles, minimum-ionizing particles, and neutrons was all demonstrated. In the case of alpha-particle detection and spectrometry, the obtainable energy resolution is dependent on the design characteristics of the SiC detector as well as on the material and electronic properties of the SiC material. In this article, we review the history of SiC alpha-particle detector development as well as the factors affecting detector performance and the prospects for further improvements. Detector design factors, including active-volume and entrance-window effects, are discussed in detail. Materials and electronic factors that influence the quality of alpha-particle detection are also discussed. These factors include SiC lattice defects, charge-carrier mobility, charge trapping, and the energy required to produce an electron-hole pair. Since the first demonstration of alpha-particle spectrometry, SiC detectors have evolved to the point that an energy resolution of 0.29% (15.9 keV full width at half maximum (FWHM) for 5485.7-keV 241Am alpha particles) has been reported. This resolution is comparable to the best obtainable with silicon alpha-particle detectors. The prospects for further improvements in alpha spectrometry with SiC detectors are also discussed.