Study Of Damage Effects In SiC Schottky Barrier Diodes Induced By Irradiations Of High-energy Protons And Heavy Ions

Silicon Carbide(SiC),the third-generation semiconductor material,has the characteristics of large band gap,high blocking voltage,low neutron capture cross-section and high threshold displacement energies.These advantages makes the SiC based semiconductor devices have important application prospects in the aerospace industry,and has become a key component in the new generation of spacecraft electric propulsion systems.The application of SiC devices in space will be affected by the radiation of various high-energy particles(especially protons and heavy ions),resulting in device performance's degradation or even failure.Therefore,studying the radiation damage effect of SiC devices is of great significance for their application in space.In this paper,we were using the HI-13 tandem accelerator in China Institute of Atomic Energy to carry out the irradiation experiments with 10 Me V,20 Me V proton and 208 Me V Ge ions beam for SiC Schottky Barrier Diodes(SBD).The damage effect and physical mechanism of SiC diode caused by proton and Ge ions irradiation were studied through testing and analysis the on-line current monitoring of the diode,the I-V characteristic curves,C-V characteristic curves,deep-level transient spectra and infrared thermal images.The results of the study are as follows:(1)Proton irradiation leads to increased defect level density and decreased carrier concentration in SiC diodes.After irradiation,the interface charge accumulated on the Schottky contact interface,resulted in the reverse current of the diode was significantly reduced.For 10 and 20 Me V proton irradiation with a fluence of 1×10¹¹p/cm~2,the diode's breakdown voltage decreased from more than 820 V to 600 V after irradiation.The electrical properties of the irradiated diodes were partially recovered after 4 months at room temperature.(2)After Ge ion irradiation,the forward electrical properties of the SiC device remained good,the barrier height and ideality factor of the device only changed slightly,and the series resistance increased significantly due to the formation of irradiation defects(carrier recombination centers)in the SiC layer.Ge ion irradiation increases the reverse current of the device by 2-3 orders of magnitude,and reduces the reverse breakdown voltage from more than 820 V to 600 V,which may be the result of the generation of micro-leakage paths.Under the same ion fluence,the diodes under biased state when irradiated show more obvious performance degradation than the unbiased diodes.(3)The biased Ge ion irradiation were continued to the SiC diodes that after proton irradiation.These diodes with higher bias voltage under irradiation experiments are more likely to occur the Single Event Burnout,which indicates that the cross-section of Single Event Burnout is proportional to the bias voltage of the device.When the bias voltage was reduced to 200 V,no burnout was observed.Under the same bias voltage,the degradation of device performance is proportional to the ion fluence.The proton pre-irradiation may inhibit the Single Event Burnout of the device under Ge ion irradiation,and the specific reason remains to be further analyzed.(4)The Silvaco simulation shows that the device's temperature and electric field increase after the Ge ion irradiation,and their value are proportional to the bias voltage of the device.The increase in electric field makes the device prone to avalanche breakdown and the Single Event Burnout,the increase in temperature makes it easier to generate micro-leakage paths.This study expounded the variation law of the basic electrical performance parameters of SiC diodes with proton and Ge ion irradiation,and clarified the influence of bias voltage and ion fluence on the irradiation effect of the device.The research results have important reference value for evaluating the radiation stability of SiC devices in space.