Study Of Neutron Detector Based On 4H-SiC PiN Diode

Relying on excellent material physical properties such as wide forbidden band,high critical displacement energy,and strong critical breakdown field,the third-generation semiconductor 4H-SiC device,to a great extent,overcame the problem of degradation of device performance or even failure of conventional Si,Ge,and GaAs-based semiconductor devices operating in harsh environments such as high temperature and strong radiation.Therefore,it has important research significance in the field of nuclear radiation detection represented by fission reactor and fusion test device neutron detection.With the improvement of the quality of 4H-SiC substrates and the continuous improvement of the process level of 4H-SiC-based devices,applications based on high-quality 4H-SiC devices have become more and more widespread,but due to limitations in materials,processes,etc,the research of the radical neutron detector is still in its infancy.At present,the research units for SiC-based neutron detection are mainly Chinese Institute of Engineering Physics and National University of Defense Technology,but these units are based on the Monte-Carlo simulation method to simulate fission neutron energy spectrum,energy collection efficiency,etc.Simulations and experiments on the core component semiconductor devices for neutron detectors have not been adequately studied.In recent years,the improvement of the quality of 4H-SiC substrates and epitaxial materials and the continuous improvement of device technology have laid a solid foundation for the preparation of high-quality 4H-SiC neutron detectors.Therefore,based on the theoretical design requirements of neutron detectors and the 4H-SiC materials with excellent performance,this paper focuses on the design of 4H-SiC-based PiNs that meet 3 MeV fast neutron detection?Double-JTE?.The device,with the aid of simulation software such as SRIM and Sentaurus,obtained the device parameters that make the PiN device have the smallest possible reverse leakage.In addition,corresponding devices whose performance meets actual requirements have been prepared through current advanced process equipment and device preparation key technologies.Then the Sentaurus simulation software was used to simulate the change law of the charge collection efficiency of the secondary charged particles alpha???and helium?³H?generated by the incident neutron generation in the PiN device,and then the prepared system was tested by an external test system.Neutron detector detection performance.The specific research contents and results mainly include the following aspects:?1?SRIM software was used to simulate the range and energy deposition information of secondary charged particles?and ³H produced by 3 MeV fast neutron cores in 4H-SiC materials,respectively,and was designed according to the neutron detector design theory.MeV neutron neutron detector basic structure and parameters.In addition,from the point of view of device structure design,in order to reduce the risk of extra electric leakage induced by high electric fields to reduce the detector's intrinsic noise,a Double-JTE terminal structure was introduced in the PiN device,and the Sentaurus software was used to detect the presence or absence of interface charges.Starting from two aspects,the simulation of the parameters of the JTE was changed to obtain the optimal Double-JTE parameter value that makes the maximum peak electric field strength of the device as small as possible.Finally,the optimal parameters of the Double-JTE based 4H-SiC PiN device in the neutron detector are obtained as follow:he thickness of P region is 0.5?m,and the doping concentration is1×10¹99 cm^-3;the thickness of I region is 100?m,and the doping concentration is 5×10¹33 cm^-3;the thickness of the N region 300?m,and the doping concentration is 5×10¹88 cm^-3.The lateral length of JTE1 and JTE2 are respectively 200?m,junction depth is 0.5?m,in which doping concentration of JTE1 is 6×10¹66 cm^-3,doping concentration of JTE2 is 3×10¹66 cm^-3.The maximum peak electric field of the designed Double-JTE terminal structure is 29.3%,lower than that of the Single-JTE,and the influence of the interface charge is relatively small.?2?According to the energy deposition information of the secondary charged particles?and3H generated in the nuclear role in 4H-SiC materials,the main factors such as working voltage,main junction thickness,incident position,and depletion region traps are simulated using Sentaurus software.Collect the impact of performance and summarize the rules.The simulation results show that under ideal conditions,the higher the operating voltage before saturation voltage,the better the charge collection performance;the thinner the main junction thickness,the smaller the energy loss,and the higher the instantaneous current pulse height,the greater the charge collection efficiency.Under the premise of other conditions being unchanged,the existence of the trap will make the instantaneous current pulse height decrease,the charge collection efficiency become smaller,and the collection time becomes longer.?3?The Double-JTE based 4H-SiC PiN device with excellent performance was prepared according to the designed device structure and parameters,and advanced technology was used.The test results show that the device has a leakage current of less than 20 nA at 800 V,which meets the design requirements..Secondly,based on the special neutron detection,preliminary charged particle detection and neutron detection were performed on the prepared4H-SiC PiN detector using a built-in neutron detection peripheral test circuit system.The test results show that the designed 4H-SiC PiN detector has a certain response to?with energy of 5.05 MeV and neutron with average energy of 2.348 MeV.