Development Of PiN Device Based On 4H-SiC High Resistance Single Crystal

As a typical representative of the third-generation semiconductor materials,silicon carbide?SiC?materials have many advantages,such as strong breakdown resistance,radiation resistance,and good thermal stability.Therefore,SiC is widely used in high-power,high-temperature,radiation-resistant and other electronic device manufacturing fields.In the field of semiconductor detectors,compared with traditional Si/Ge semiconductor detectors,SiC has obvious advantages,it has the advantages of high temperature resistance,radiation resistance and strong resistance to penetration.In recent years,the development of silicon carbide nuclear radiation detector has become a hot field in the world.In this paper,the PiN device for high energy X-ray detection is developed by using the thickness advantage of 4H-SiC single crystal,and systematically analyzes the prepared devices by means of simulation and experiments.The process of silicon carbide ion implantation is simulated by SRIM simulation software.The ion implantation in N and P region of PiN diode is simulated.The depth,energy and distribution of ion implantation were simulated.The distribution of ion implantation was obtained when the thickness was 300nm and the concentration of N,B,Al and P ions was 10¹⁹cm^-3.Using Silvaco TCAD software,the electrical characteristics of the device are simulated,and the information such as the opening voltage,leakage current and electric field distribution of PiN device are extracted,and compared with the later experimental results.According to the optimized parameters obtained by simulation,the ion implantation experiments are carried out,and boron ion and nitrogen ion are selected to form the P-region and N-region of the device.In order to improve the surface morphology damage and ion precipitation in the process of ion implantation and annealing,a 25nm AlN mask was sputtered on the Si?Implanted B ions?side of SiC single crystal by magnetron sputtering.We analyzed the morphology,crystal quality and element composition of the sample before and after ion implantation and annealing,and found that the lattice damage caused by ion implantation would recover significantly in the process of annealing activation.SEM results showed that the presence of AlN mask can play an obvious role in surface protection during annealing.In the aspect of electrical test,the surface resistivity of C?Implanted N ions?side of SiC was measured by van der Pauw's method,and it was calculated that the surface resistivity of the sample after N-ion activation was about 0.068?.cm.Finally,the electrode was prepared by thermal evaporation method.The preparation process of ohmic contact electrode in N-region and P-region is the same,both of them are of Al/Ti/Au structure,the annealing temperature is 880?,and the annealing atmosphere is nitrogen.Then the current voltage test of the PiN device was carried out.The leakage current of the device was 2 10^-9A,when the reverse voltage was 50 V,and the forward opening voltage was 1.98 V.