Nonequilibrium Carrier Diffusion and Recombination in Heavily-Doped and Semi-Insulating Bulk HTCVD Grown 4H-SiC Crystals
We applied four-wave mixing (FWM) technique for investigation of high temperaturechemical vapour deposition (HTCVD) grown 4H-SiC samples with different doping levels. The determined minority electron and hole mobilities in heavily doped crystals at doping densities of 1019 cm-3 were found to be equal to 116 and 52 cm2/Vs. In semi-insulating (SI) crystals, the ambipolar diffusion coefficient Da = 2.6 − 3.3 cm2/s and carrier lifetimes of 1.5 – 2.5 ns have been measured. Irradiation of SI crystals by 6 MeV electrons resulted in essential decrease of carrier lifetime down to ~ 100 ps and clearly revealed the defect-assisted carrier generation with respect to two-photon interband transitions before irradiation.
Dr. Roberta Nipoti, Antonella Poggi and Andrea Scorzoni
L. Storasta et al., "Nonequilibrium Carrier Diffusion and Recombination in Heavily-Doped and Semi-Insulating Bulk HTCVD Grown 4H-SiC Crystals", Materials Science Forum, Vols. 483-485, pp. 409-412, 2005