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 ${\text{1×10}}^{12}\hspace{0.17em}{\mathrm{cm}}^{\text{−2}}$ creates an estimated initial concentration of intrinsic point defects of about ${10}^{14}\hspace{0.17em}{\mathrm{cm}}^{\text{−3}}$ 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, $M_1$ and $M_3$ at $E_C\text{−0.42}$ and around $E_C\text{−0.75\hspace{0.17em}}\mathrm{eV},$ respectively, in one configuration and one peak, $M_2$ at $E_C\text{−0.70\hspace{0.17em}}\mathrm{eV}$ 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.