Suppression of the Carbon Vacancy Traps and the Corresponding Leakage Current Reduction in 4H-SiC Diodes by Low-Temperature Implant Activation in Combination With Oxidation

Abstract

Junction barrier Schottky diode fabrication involves multi-folded Al ion implantation for realizing p-type doping. With a new fabrication recipe, we demonstrate that the trade-off between sufficiently high Al acceptor activation and sufficiently low residual concentration of carbon vacancies - acting as free carrier traps - may be resolved applying relatively low temperature anneals (1700°C), followed by the thermal oxidation which leads to in-diffusion of the carbon interstitials from the C-rich sacrifice-oxide/SiC interface. Specifically, we detected two major interconnected factors: suppression of the carbon vacancies and dramatic reduction of the reverse leakage current (by 32 times at -1200 V). The reduction of the reverse biased current is correlated with the removal of the carbon vacancies, interconnected with the Poole-Frenkel emission contribution to the leakage current.