An overview of application of 4H-SiC n-type epitaxial Schottky barrier detector for high resolution nuclear detection

Availability of high-quality bulk and epitaxial 4H-SiC has revived the feasibility of fabrication of nuclear radiation detectors which are compact, operable at room or elevated temperature, physically rugged, and radiation hard. SiC detectors have been demonstrated as excellent alpha particle detectors and hence are being considered as compact neutron detectors when coupled with neutron-alpha conversion layers. Our group at University of South Carolina has successfully demonstrated the fabrication of large area (~11 mm²) 4H-SiC epitaxial surface barrier type sensors, for detection of x-rays of energy as low as 50 eV with very high responsivity, high resolution detection of low energy gamma rays (2.1% FWHM for 59.6 keV gamma rays) and very efficient and high-resolution alpha particle detection. We have recently fabricated surface barrier detectors for alpha particles with an energy resolution of 0.29% for 5.48 MeV alpha particles, the best value reported till date, with a charge collection efficiency (CCE) ~100%. These detectors have also shown a CCE more than 57% at zero applied bias for 5.48 MeV alpha particles which opens up the possibility of highly efficient bias-less operation, a much sought-after quality for field deployment of stand-off detection system for Homeland security applications. We have performed a noise analysis in terms of equivalent noise charge and we have found that the white series noise due to the detector capacitance has substantial effect on their spectroscopic performance. We have also studied the effect of the presence of electrically active defects on detector performance using deep level transient spectroscopy measurements.