Bistable defect in mega-electron-volt proton implanted 4H silicon carbide

Epitaxial 4H-SiC n-type layers implanted at room temperature with a low fluence of mega-electron-volt protons have been measured by deep level transient spectroscopy (DLTS). The proton fluence of 1×1012 cm−2 creates an estimated initial concentration of intrinsic point defects of about 1014 cm−3 of which about 10% remain after the implantation and gives rise to deep states in the upper part of the band gap. Here, we investigate the samples prior to high-temperature annealing and a very complex spectrum is revealed. In particular, a bistable defect M is discovered having two DLTS peaks, M1 and M3 at EC−0.42 and around EC−0.75 eV, respectively, in one configuration and one peak, M2 at EC−0.70 eV in the other configuration. The charge dependent thermal activation energies for the transformation between the bistable defect peaks are 0.90 and 1.40 eV.