Development Of 4H-SiC Nuclear Radiation Detector

Compared with other nuclear radiation detectors,semiconductor nuclear radiation detectors have significant advantages such as small size and excellent energy resolution.In comparison with the first generation of semiconductors,such as Si and Ge as well as the second type of semiconductors represented by compounds such as Ga As and Cd Te,SiC and diamond have their own material advantages such as greater band gap,higher thermal conductivity and stronger radiation resistance,but due to the high cost of high-purity single crystal diamond,SiC is considered as an ideal material for manufacturing high-temperature and radiation-resistant detectors.In contrast to the physical properties of the three most common allotropes of SiC materials,as well as the research progress at home and abroad,4H-SiC nuclear radiation detectors as the research focus of wide bandgap semiconductor detectors,have extensive applications and research in the field of nuclear science and technology.In this context,this paper mainly does the following work:1.The types of ionizing radiation,the process of interaction between common radiation particles and matter are described,the classification overview and principle explanation of the categories of nuclear radiation detectors are made,and the advantages of 4H-SiC nuclear radiation detectors in some special application scenarios are highlighted by comparing the principles and characteristics of gas radiation detectors,scintillator radiation detectors and the first and second generation semiconductor radiation detectors.The material properties of4H-SiC are briefly introduced,and the TRIM module in the SRIM 2013 program is used to calculate whether the thickness of the epitaxial layer meets the experimental requirements involved in this paper,and the 4H-SiC detector is determined to be a Schottky diode structure based on the calculation results,and some significant parameters of the semiconductor nuclear radiation detector are briefly derived.2.The influence of slow annealing process on the performance of the prepared 4H-SiC detector in the vacuum environment of ohmic electrode was summarized,under the same cleaning process and electrode preparation process,only adjusting annealing temperature of the ohmic contact electrode,the detectors prepared at different annealing temperatures were tested and compared.The results of the I-V characteristic test,the full depletion voltage test,and the operation stability capability at high voltage were analyzed,and the relatively best process in this paper was obtained.At 120 V total depletion voltage,the ohmic electrode undergoes slow annealing at 800°C with the best electrical performance,reverse leakage current of less than 1 n A,and energy resolution of 1.36%for ²⁴¹Am particles.At a high voltage of 200 V,the leakage current is still less than 1 n A and the energy resolution is1.40%,which proves that the detector can operate stably at higher voltages.The reverse I-V characteristics test of the detector in high temperature environment showed that the prepared detector still had well electrical properties at 200°C,and the XRD test results of the electrode proved that Ni formed a superior contact with 4H-SiC.A feasible process and method for the preparation of 4H-SiC detectors were found.3.In view of the advantages of strong radiation resistance of 4H-SiC,combined with the fact that 4H-SiC is mostly used in harsh environment such as high temperature and strong radiation,high-flux proton and heavy ion beam irradiation experiments were carried out on4H-SiC detector.The heavy ions used were Fe¹³⁺and C⁴⁺,and the performance changes of the detector after being irradiated by ion beam with different fluxes were tested.Since carbon ions are widely used in radiation medicine,the performance of 4H-SiC detectors irradiated by C⁴⁺was also tested under high temperature conditions.The test results show that 1×10¹⁷n/cm²proton beam irradiation has little effect on the overall performance of 4H-SiC detector,which still maintains excellent performance after irradiation.For the effect of Fe¹³⁺and C⁴⁺beam irradiation on detector performance,the degradation of both electrical performance and detection performance is small at a flux of 1×10¹³n/cm²,but the performance of the detector gradually deteriorates as the ion beam flux increases.When the Fe¹³⁺beam flux reaches4×10¹³n/cm²,the reverse leakage current of the detector has increased to 9μA,and after the C⁴⁺irradiation dose increases to 1×10¹⁵n/cm²,the reverse leakage current of the detector at200 V voltage increases to 6.18μA.The limit irradiation flux of the detector damaged was found through comparison of several sets of tests,which may be used in the future for the main beam monitoring or the direct detection of heavy ions and other related nuclear tests.