PHOTOELECTROCHEMICAL CHARACTERIZATION OF 6H-SIC

Photoelectrochemical methods were used to characterize n-type 6H-SiC. The double layer capacitance obeyed the Mott-Schottky relationship ove r 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 potenti al dependence of the photocurrent was 30 nm. From the dependence of th e photocurrent on the photon energy, the absorption coefficient alpha( h nu) was determined using the Gartner model. The results are in excel lent agreement with spectra reported in literature. Sub-band-gap photo current with photons of energy down to 1.96 eV (approximate to 1 eV be low the band gap) was also observed. (C) 1998 American Institute of Ph ysics. [S0021-8979(98)00411-3]