Pinning Effect on Fermi Level in 4H-SiC Schottky Diode Caused by 40-MeV Si Ions

The changes in the electrical properties of 4H-SiC Schottky diodes caused by 40-MeV Si ions with different fluences are investigated. The irradiation fluences are selected as 1.0 × 10⁹ , 8.9× 10⁹ , and 1.5 × 10¹⁰ cm^-2, respectively. The diodes were characterized using deep-level transient spectroscopy (DLTS) and Keithley 4200-SCS semiconductor characterization system. The TRIM software is used to estimate the carbon distribution of vacancies in the irradiated 4H-SiC diodes by 40-MeV Si ions. As irradiation fluence increases, the ideality factors increase from 1.01 to 1.09, while the Schottky barrier height decreases from 1.16 to 1.09 eV. The free-carrier concentration N_d decreases with the increasing fluence from 1.0 × 10⁹ to 1.5 × 10^10 cm^-2. The free-carrier removal rate is estimated to be 2.4 × 10⁶ cm^-1. Experimental and simulated results show that 40-MeV Si ions produce high concentrations of displacement defects (Z1/Z2 center) in the 4H-SiC, leading to the Fermi level to be pinned at the deep levels.