Reduction of traps and improvement of carrier lifetime in 4H-SiC epilayers by ion implantation

The authors report a significant reduction in deep level defects and improvement of carrier lifetime in 4H-SiC material after carrying out carbon or silicon ion implantation into the shallow surface layer of 250nm and subsequent annealing at 1600°C or higher temperature. Reduction of Z1∕2 and EH6∕7 traps from 3×1013cm−3 to below the detection limit (5×1011cm−3) was observed by deep level transient spectroscopy in the material 4μm underneath the implanted layer. Minority carrier lifetime almost doubled in the implanted samples compared to the unimplanted samples. The authors propose that the implanted layer acts as a source of carbon interstitials which indiffuse during annealing and accelerate annealing out of grown-in defects in the layer underneath the implanted region.