碳化硅探测器的最大线性电流研究

Investigation of Linear Current in SiC Radiation Detector

本文研究了电流型碳化硅探测器的最大线性电流特性,给出了最大线性电流计算方法,分析了辐射类型、灵敏区面积、灵敏区厚度和耗尽区电场强度对最大线性电流的影响,利用强脉冲X射线加速器和紫外激光源实验研究了碳化硅探测器的最大线性电流特性。研究结果表明,灵敏区面积4 cm^(2)的碳化硅探测器可获得4 A以上的线性电流,不同规格碳化硅探测器最大线性电流的理论和实验结果最大相对偏差约23%。

Diagnosis of pulsed neutron emitted by nuclear fission is one of key methods to study nuclear reaction mechanism.It is not easy to get accurate neutron parameters for the intense radiation background,composited of scatter neutron,gamma ray,etc.Aiming at the demands of the pulsed fission neutron detection,the detection method with high linear current,high neutron/gamma discrimination,high neutron/scatter neutron discrimination,low dark current etc.should be developed,in which high-performance detector is the most important component.However,traditional semiconductor detectors are difficult to meet these requirements,which has become a bottleneck restricting the research of nuclear reaction mechanism and an international technical problem.Thus,it is necessary to develop new radiation detectors.The wide-gap semiconductors have good potentials in radiation detection of intense radiation field and high temperature,which are not only with higher displacement energy(about 20-109 eV)than silicon(13 eV),resulting in their high radiation resistance,but also have higher thermal conductivity and melting points temperature than the traditional silicon material(1412℃and 1.5 W·cm^(-1)·K^(-1),respectively),promising possibility of withstand wide operable temperature range.The high breakdown strength together with proper doping concentration determines the proper depleted width for secondary charged particle detection.Silicon carbide(SiC)is one of the most important wide-gap semiconductors.The mature of epitaxial material makes it possible to fabricate lightly doped high-quality SiC material with thin thickness,thus thin SiC detectors could be developed for the intense pulsed neutron detection with good resistance to high voltage,high charge collection efficiency,good endurance in intense radiation field and high temperature environment,furthermore it is expected to significantly improve the pulsed neutron detection technology.Linear current is an important characteristic for SiC detector in intense pulsed radiation detection,which determines the output upper limit and detectable dynamic range of the detection system.However,studies on the maximum linear current of current-type SiC detectors are far from fully investigated.In this paper,calculation method of linear current was established effectively,furthermore,the influence of radiation type and SiC detector’s sensitive area,sensitive thickness and electric strength were analyzed carefully.Experimental linear current is acquired at UV laser equipment and pulsed X-ray generator,indicating a result of higher than 4 A for a SiC detector with a sensitive area of 4 cm^(2) and a reverse bias of 400 V.The maximum relative deviation between theoretical and experimental results is about 23%.