Akira Tsumura

Electro-and photo-luminescence spectra in various n-type semiconductors in relation with anodic reaction intermediates

Abstract Electroluminescence spectra of n-type semiconductor electrodes - GaP, CdS, ZnO and TiO2 - caused by the presence of oxidants are studied, together with luminescence spectra of these semiconductors caused by photoexcitation. Parts of the luminescence bands are tentatively interpreted to be due to surface-trapped holes, which act as a precursor of photo- anodic reactions, similar to the case of n-GaP.

Photoanodic Dissolution Reaction of an n‐Type Gallium Phosphide Electrode and Its Effect on Energies of the Electronic Bands at the Surface

Mott‐Schottky plots obtained at dark and under weak illumination have shown that the energies of the electronic bands at the surface of an electrode are sifted downward, toward more negative, by illumination under anodic polarization. The magnitude of the shift for the (111)‐face of the electrode was somewhat smaller than that for the (111)‐face. The results are explained by taking account of photoanodically formed surface intermediates, causing a change in the potential difference at the semiconductor‐solution interface. These intermediates were found to decay in several minutes at dark under anodic polarization. It is suggested that these intermediates also act as effective surface recombination centers.