High energy electron radiation effect on Ni/4H-SiC SBD and Ohmic contact

The Ni/4H-SiC Schottky barrier diodes (SBDs) and transfer length method (TLM) test patterns of Ni/4H-SiC Ohmic contacts were fabricated, and irradiated with 1~MeV electrons up to a dose of 3.43× 10¹⁴~e/cm^-2. After radiation, the forward currents of the SBDs at 2~V decreased by about 50%, and the reverse currents at -200~V increased by less than 30%. Schottky barrier height (φ _B ) of the Ni/4H-SiC SBD increased from 1.20~eV to 1.21~eV under 0~V irradiation bias, and decreased from 1.25~eV to 1.19~eV under -30~V irradiation bias. The degradation of φ _B could be explained by the variation of interface states of Schottky contacts. The on-state resistance (R_s) and the reverse current increased with the dose, which can be ascribed to the radiation defects in bulk material. The specific contact resistance (\rho_c) of the Ni/SiC Ohmic contact increased from 5.11× 10⁵~Ωega.cm² to 2.97× 10^-4~Ωega.cm².     

Ni/4H-SiC肖特基势垒二极管的γ射线辐照效应

对制备的Ni/4H-SiC肖特基势垒二极管（SBD）进行了γ射线辐照试验,并在辐照过程中对器件分别加0和-30?V偏压.经过1?Mrad（Si）总剂量的γ射线辐照后,不同辐照偏压下的Ni/4H-SiC肖特基接触的势垒高度和理想因子没有退化,SiC外延层中的少子寿命也没有退化.辐照后器件的反向电流下降,这是由于器件表面的负界面电荷增加引起的.研究表明,辐照偏压对Ni/4H-SiC SBD的辐照退化效应没有明显的影响. 关键词： 碳化硅 肖特基 辐照效应 偏压     

High energy electron radiation effect on Ni and Ti/4H-SiCSchottky barrier diode at room temperature

This paper reports that Ni and Ti/4H-SiC Schottky barrier diodes (SBDs) were fabricated and irradiated with 1~MeV electrons up to a dose of 3.43×10¹⁴~e/cm². After radiation, the Schottky barrier height φ _B of the Ni/4H-SiC SBD increased from 1.20~eV to 1.21~eV, but decreased from 0.95~eV to 0.94~eV for the Ti/4H-SiC SBD. The degradation of φ _B could be explained by interface states of changed Schottky contacts. The on-state resistance R_S of both diodes increased with the dose, which can be ascribed to the radiation defects. The reverse current of the Ni/4H-SiC SBD slightly increased, but for the Ti/4H-SiC SBD it basically remained the same. At room temperature, φ _B of the diodes recovered completely after one week, and the R_S partly recovered.