Photoelectrochemical characterization of 6H-SiC

Photoelectrochemical methods were used to characterize n-type 6H-SiC. The double layer capacitance obeyed the Mott-Schottky relationship over a large potential range (>6 V band bending). The flat-band potential was found to depend on pH with a displacement of about 40 mV per unit pH. The minority carrier diffusion length determined from the potential dependence of the photocurrent was 30 nm. From the dependence of the photocurrent on the photon energy, the absorption coefficient alpha(h nu) was determined using the Gartner model. The results are in excellent agreement with spectra reported in literature. Sub-band-gap photocurrent with photons of energy down to 1.96 eV (approximate to 1 eV below the band gap) was also observed. (C) 1998 American Institute of Physics. [S0021-8979(98)00411-3]