Investigation of Current Doubling Reactions at SiC/Aqueous Electrolyte Junction in Relation to the Band Energetics

The current doubling behaviour of organic reagents especially alcohols by oxidation and persulfate by reduction was studied at n‐ and p‐SiC single crystals, respectively. In the case of n‐SiC no photocurrent increase was observed even under the acidic conditions with the addition of iso‐propyl alcohol whose alcohol radical potential lies most negative among the alcohols used. This implies that the conduction band position of n‐SiC is very negative. The radical intermediates formed during irradiation of n‐SiC suspension in various alcohols were analyzed by ESR spin trapping technique. On the other hand, current doubling behaviour was observed at p‐SiC during the reduction of persulfate ion by a hole injection into the valence band. This hole injection process was also confirmed by the EL (electroluminescence) studies. These results are discussed in terms of the interface energetics of SiC/aqueous electrolyte junction.