High-Resolution Cr/4H-SiC Schottky Barrier Radiation Detector

In this article, we present the first comprehensive analysis of radiation detection using chromium (Cr) as the Schottky barrier contact on n-type 4H-silicon carbide (4H-SiC) epitaxial layers tailored for high-performance applications in extreme environments. The Cr/4H-SiC Schottky barrier diode (SBD) is evaluated across several critical metrics, including junction properties, radiation response, and defect characteristics, and is compared with SBDs utilizing other refractory metals such as molybdenum (Mo), palladium (Pd), and nickel (Ni) on analogous 4H-SiC epilayers. Despite the lower work function of Cr, 4.5 eV, compared to the other metals, the Cr/4H-SiC SBDs demonstrated exceptional rectification behavior, achieving a barrier height of 1.13 eV and a low leakage current of 6.7 nA at −100 V reverse bias. These characteristics are ideal for high-resolution radiation detection applications. The Cr/4H-SiC SBD exhibited an impressive energy resolution of 0.5% at an optimized bias of −40 V when exposed to 5486-keV alpha particles. Notably, in self-biased mode (0 V applied bias), the device delivered an energy resolution of 2.3% and a charge collection efficiency (CCE) of 73%, surpassing the performance of benchmark Ni/4H-SiC SBDs. Capacitance-mode deep-level transient spectroscopy (DLTS) analysis revealed the presence of key deep-level defects, including Z<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{1/2}$ </tex-math></inline-formula> and EH5 trap centers, and titanium substitutional defects. Among these, the Z<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}_{1/2}$ </tex-math></inline-formula> trap center, widely regarded as a lifetime-killer, was found to play a significant role in influencing the detector’s performance. The findings in this article highlight the untapped potential of Cr/4H-SiC SBDs for high-efficiency, self-biased radiation detection in harsh environments, such as nuclear reactors and space exploration missions.