Study On The Effects Of Z_1/2 Defect On The Performance Of SiC Detector

With the continuous expansion of the field of human cognition,astrospace has gradually become the hotspots of scientists domestic and overseas,and space particle detection has become the basic method and primary condition for human beings to understand,study and explore space.Therefore,it is necessary to research and develop space particle detectors.Space particle detectors generally work in extreme environments of high temperature,high pressure and strong radiation.However,the commonly used gases,scintillator and conventional semiconductor detectors can only work at room temperature or low temperature.Thus,there is an urgent need to develop a new type of detector that can work in harsh conditions.At present,the third generation wide bandgap semiconductor material silicon carbide have become a research hotspot in high temperature and strong radiation field because of its superior properties,such as high critical breakdown field,large displacement threshold energy,high thermal conductivity and high electron saturation drift velocity.Nevertheless,the Z_1/2 defect has a significant effect on carrier lifetime of silicon carbide materials,as a result,the working life,detection efficiency,energy resolution and sensitivity of SiC detectors are affected severely.In order to analyze the influence of Z_1/2defects on the performance of SiC detectors,a method for calculating pulse height spectrum is proposed.In this paper,for the specific 4H-SiC neutron detector structures,the feasibility of the calculation method was investigated,the neutron pulse height spectra under different conditions were calculated and compared with the experimental results.The major works in the parper are presented as the following.（1）The calculation method was verified by using the 4H-SiC Schottky diode neutron detector.The output voltage pulses of the 4H-SiC Schottky diode to 5.486 MeV alpha particles and the pulse height spectrum of the detector to 0.026 eV thermal neutrons were calculated.Moreover,Comparisons of the simulated results with the experimental data were also presented.Meanwhile,output current pulses,charge collection efficiency and output voltage pulses of the detector under various situations were analyzed.The simulation results are in good agreement with the experimental results,which confirms that the calculation method adopted in this paper is reliable and applicable.In addition,the simulations show that output current,charge collection efficiency and output voltage of the detector are related to the applied bias voltage,the incident angle and energy of the particle.（2）The neutron spectra response with the Z_1/2 defect were calculated using the 4H-SiC PIN diode neutron detector.Firstly,the neutron pulse height spectra under different carrier lifetimes without Z_1/2 defect were calculated.It is found that when the electron and hole lifetimes are 50 ns and 20 ns,respectively,the calculated neutron energy spectrum has a similar shape to the experimental energy spectrum.Accordingly,it is suggested that the minority carrier lifetime of the detector in the experiment may have changed before using.Then,the neutron pulse height spectra under various Z_1/2 defect concentrations with the minority carrier lifetime of 2μs were calculated.It is indicated that the peak of the neutron pulse height spectrum is mainly caused by ³H particles.It can be deduced that the Z_1/2defect concentration in the 4H-SiC PIN diode neutron detector used in the experiment is within the range of 7×10¹³⁹×10¹³ cm^-3.Furthermore,when the Z_1/2 defect concentration is as high as 1×10¹⁵ cm^-3,the detector can not work normally.There is a gap between simulation results and experimental results.In general,Z_1/2 defect has a considerable influence on the neutron energy spectrum,resulting in deterioration of detector performance.In summary,the calculation method proposed in this paper is workable and suitable,and the Z_1/2 defect has obvious impact on the performance of SiC detectors.This work provides a new method and idea for calculating the pulse height spectrum ofαparticles,³H particles,neutrons and other radiation particles.It is also helpful and useful for the development and design of new-type SiC detectors in the future.