Electrical and low frequency noise properties of 4H-SiC p+-n-n+ junction diodes

The electrical and low frequency noise properties of 4H-SiC p(+)-n-n(+) junctions have been investigated at different temperatures. The forward current-voltage characteristics are described as the sum of a recombination current originating from carrier recombination on the sidewall of the circular mesa of the diodes and a diffusion volume current. In the current region where the recombination mechanism is dominant, the main noise sources are attributed to carrier recombination at the perimeter surface of the diode and to a generation-recombination noise related to a local trap level. In the current region where the diffusion current becomes important, the noise originates from mobility and diffusivity fluctuations in the space charge region of the p(+)-n junction. Analysis of the current and noise data allowed us to determine the density of surface states and the Hooge factor, characterizing the surface and the bulk quality of the diode. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.