Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)

O 58.4: Poster

Mittwoch, 28. März 2012, 18:15–21:45, Poster B

Charge transfer processes in platinum-silicon-diodes induced by electrochemical surface reactions at the platinum-sulfuric acid interface — •Damian Bürstel and Detlef Diesing — Fakultät für Chemie, Universität Duisburg-Essen, D-45117 Essen, Germany

Schottky diodes consisting of a 16 nm platinum film as electrochemical working electrode and a n-doped Si<111>-substrate as back electrode are used to study the energy dissipation and charging effects of the platinum film induced by electrochemical surface reactions. For this purpose cyclovoltammetric experiments are carried out in 1 M sulfuric acid and the charge transfer processes between the platinum and the silicon back electrode is measured as a current j_dev during this experiments. Furthermore these processes are studied as a function of the internal barrier height varied by applying a bias U_bias at the silicon back electrode. The current j_dev may monitor excitations and also heating effects of the platinum film since diodes with a low internal barrier are sensitive for excitations with very small energies. It is shown that j_dev depends significantly on U_bias which is comparable with results from photo excitation experiments for these devices. An additional current in j_dev is measured in the H_upd region. This effect can be explained by a modification of the internal field of the diode due to a shift in the chemical potential caused by the adsorption of hydrogen. This shift can achieve values of 20 mV for the whole H_upd region. Sulfate and oxygen adsorption have a much smaller effect on the chemical potential of the film.