Electrochemistry of anodic etching of 4H and 6H–SiC in fluoride solution of pH 3

Electrochemical etching of single-crystal SiC rotating disk electrodes in fluoride solution was studied at pH 3. Anodic dissolution and passivation are observed for p-type electrodes in the dark and for n-type electrodes under illumination. The dissolution of p-type (0 0 0 1) 4H–SiC is found to be under mixed transport/kinetic control; the diffusion current is first order in fluoride concentration. Polishing of p-type electrodes can be achieved at rates up to 5.8 μm/min. Porous etching was not observed in this case. The surface finish of n-type (0 0 0 1) 4H and 6H–SiC depends on the experimental conditions; both uniform and porous etching are observed. The results are compared with those of Si under comparable conditions.