Speaker
Description
Future high-energy physics facilities (HL-LHC, CEPC, FCC) and nuclear fusion experiments require detectors with superior radiation tolerance and high time resolution. Silicon carbide (SiC) has emerged as an ideal candidate to replace conventional silicon-based detectors, owing to its wide bandgap, high displacement threshold energy, high thermal conductivity, high critical breakdown electric field, and high saturated electron drift velocity. These properties give rise to the outstanding radiation hardness, high-temperature stability, and fast response capability of SiC. This study systematically investigates three device types: 4H-SiC PIN detectors, graphene-enhanced 4H-SiC PIN detectors, and 4H-SiC low-gain avalanche diodes (LGAD), focusing on device performance optimization and radiation tolerance evaluation. For PIN detectors, under Ta heavy-ion irradiation at 16 MeV/u with fluences from 1×10⁹ to 1×10¹² cm⁻², the I V and C V characteristics remain stable, and time resolution degrades slightly from 38.1 ps to 53.4 ps, demonstrating excellent resistance to heavy-ion irradiation. However, under proton irradiation at 7×10¹³ p/cm², the alpha-particle charge collection efficiency (CCE) decreases significantly to approximately 30% of its pre-irradiation value. To extend SiC detector applications to low-energy soft X-ray, alpha-particle, and ultraviolet detection, a graphene-enhanced SiC PIN detector is developed. Transient current technique (TCT) measurements show that conventional open-window electrode detectors exhibit severe position-dependent timing degradation, from approximately 20 ps near the electrode to over 100 ps at the active-area center. In contrast, the graphene-enhanced detector maintains stable time resolution of approximately 20 ps across the entire active area, demonstrating that the graphene electrode effectively eliminates position-dependent degradation. Time-resolution measurements using a ⁹⁰Sr beta source show that the graphene-enhanced detector achieves 58.0±2.8 ps, a 39.6% improvement over the ring-electrode detector (96.0±3.9 ps). After 1 MGy X-ray irradiation, time resolution degrades by only 4.3 ps to 62.3±2.9 ps. Furthermore, the I V, C V characteristics and signal rise time remain stable under 1 MGy X-ray and 3.5×10¹³ neq/cm² proton irradiation, confirming excellent timing precision and radiation hardness. To improve the SNR via avalanche multiplication, the first 4H-SiC LGAD device (SICAR) with a full-epitaxial structure is successfully developed. Following proton irradiation at 80 MeV and 2.5×10¹³ p/cm², the CCE remains approximately 57% of its pre-irradiation value. Based on these performance advantages, the 4H-SiC detectors have been successfully applied to fusion plasma diagnostics, the CEPC luminosity monitor prototype and the CSNS beam monitoring system, advancing the independent innovation and engineering application development of wide-bandgap semiconductor radiation detectors.
