Comparison of 4H-SiC Radiation Detectors Based on PN Junctions and Schottky Contacts

Silicon carbide (SiC) is a material that shows great promise in the fabrication of semiconductor radiation detectors intended for harsh environments, such as space missions, nuclear reactors, or direct neutron detection. This is primarily attributable to its outstanding radiation hardness and thermal stability. The present work proposes a comparative study of two types of SiC detectors based on different blocking type systems: PN junction and Schottky contact. All detectors were fabricated from 350 µm-thick 4H-polytype-SiC substrates with various thicknesses of epitaxial layers forming the active region. Detectors with three different thicknesses of the epitaxial layer were evaluated for each detector type: 20, 60, and 100 µm for PN junction detectors, and 25, 50, and 100 µm for Schottky detectors. An investigation was conducted to establish a comparison between the electrical properties and alpha spectrometric performance of the samples. Current-voltage measurements revealed a lower leakage current in Schottky-type detectors, resulting in reduced detector noise. Alpha spectra demonstrated better energy resolution for Schottky-contact detectors. Detectors with intermediate epitaxial layer thicknesses (50–60 µm) exhibited optimal performance, characterized by low leakage current, moderate depletion voltage, and efficient charge collection. Conversely, very thin layers resulted in incomplete charge collection, while the thickest layers required high bias voltages and exhibited increased leakage currents. The findings of this study underscore the technological benefits of Schottky contacts and the necessity of optimized epitaxial layer design.