Reduction of Traps and Improvement of Carrier Lifetime in SiC Epilayer by Ion Implantation
Reduction in deep level defects and increase of carrier lifetime in 4H-SiC epilayer was observed after carbon ion implantation into the shallow surface layer of 250 nm and subsequent annealing above 1400 °C. The concentration of Z1/2 and EH6/7 traps was determined by deep level transient spectroscopy 4 μm below the implanted layer. After annealing, concentration of both traps decreased from 1013 cm-3 range to below the detection limit. Minority carrier lifetime almost doubled in the implanted samples compared to the unimplanted samples. We suggest that carbon interstitials from the implanted layer in-diffuse into the layer underneath during annealing and annihilate with carbon vacancies. Our results indicate that Z1/2 and EH6/7 traps are most likely carbon vacancy related.
N. Wright, C.M. Johnson, K. Vassilevski, I. Nikitina and A. Horsfall
L. Storasta and H. Tsuchida, "Reduction of Traps and Improvement of Carrier Lifetime in SiC Epilayer by Ion Implantation", Materials Science Forum, Vols. 556-557, pp. 603-606, 2007