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 250 nm and subsequent annealing at 1600 °C or higher temperature. Reduction of Z_1/2 and EH_6/7 traps from 3×10¹³ cm^-3 to below the detection limit (5×10¹¹ cm^-3) was observed by deep level transient spectroscopy in the material 4 μm 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.