Ar annealing at 1600°C and 1650°C of Al+ implanted p+/n 4H-SiC diodes: analysis of the J-V characteristics versus annealing temperature

We report on the electrical characterization of Al+ implanted p+/n 4H-SiC diodes via a planar technology. Hot implantation at 400°C and post implantation annealing at 1600°C and 1650°C in high purity Argon ambient were done for the realization of p+/n diodes. The current voltage characteristics of the p+/n diodes and the resistivity of the implanted layer were measured at room temperature. The majority of the 136 measured diodes had a turn on voltage of 1.75 V for both annealing temperatures. The 1600°C annealed diodes showed an almost exponential forward characteristic with ideality factor equal to 1.4, an average reverse leakage current density equal to (4.8 ± 0.1)×10-9 A/cm2 at -100 V, and a break down voltage between 600 and 900V. The 1650°C annealed diodes often had forward "excess current component" that deviates from the ideal forward exponential trend. The average reverse leakage current density was equal to (2.7 ± 0.5)×10-8 A/cm2 at -100 V, and the breakdown voltage was between 700 and 1000V, i.e. it approached the theoretical value for the epitaxial 4H-SiC layer.