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 degrees C or higher temperature. Reduction of Z(1/2) and EH6/7 traps from 3x10(13) cm(-3) to below the detection limit (5x10(11) cm(-3)) was observed by deep level transient spectroscopy in the material 4 mu m 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. (c) 2007 American Institute of Physics.