Steven N. Frank

Semiconductor Electrodes XI . Behavior of n‐ and p‐Type Single Crystal Semconductors Covered with Thin Films

Single crystal semiconductors (n-Si, p-Si, n-GaAs, p-GaAs, n-GaP, n-In.P, and n-CdS) were coated with n-type TiO~ by a chemical vapor deposition technique, and the electron and hole transfer properties across the heterojunction so produced were investigated. The quality of the deposited TiO~ film depended upon several factors including temperature and substrate material. When high quality crack-free TiO2 coats were obtained on n-type substrates, the substrate was stabilized with no dissolution during the photo-oxidation of water. However, the oxidation was due o~y to the photoexcitation of the TiO~, and any holes produced in the substrate were not transferred through the TiO~ to the solution. The use of p-type substrates coated with TiO2 as photocathodes was limited by band-bending requirements at the p-n heterojunction and the TiO~-solution interface.

Electrochemical Oxidation of Iminobibenzyl and Related Compounds

Electrochemical oxidation of iminobibenzyl and several related compounds has been investigated in acetonitrile. The mechanism of the oxidation is best described by an ECE process with coupling of the product of an initial oneelectron oxidation in a subsequent but very fast reaction to form a dimeric compound that is further oxidized by an over-all two-electron process at potentials more negative than those required for oxidation of the parent compounds. The electrochemistry of these compounds is complicated by the release of protons during the oxidation which protonate the starting materials and the neutral dimerized products rendering them electrochemically inactive. Differences in the electrochemistries of the various coupled products are discussed in terms of structural variations.