Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 20: Solid / liquid interfaces II
O 20.6: Vortrag
Montag, 14. März 2011, 18:30–18:45, WIL B321
Electrochemical studies of excited charge carriers with thin platinum film electronic devices in sulfuric and hydrochloric solution — •Damian Bürstel, Michael Scheele, Andreas Barmscheid, Kevin Stella, and Detlef Diesing — Fakultät für Chemie, Universität Duisburg-Essen, D-45117 Essen, Germany
Excited charge carriers induced by chemical processes like the adsorption or desorption of atomic hydrogen at metal surfaces have already been investigated under UHV conditions. These carriers can be detected by systems with an internal electric barrier, like MIM-(metal–insulator–metal), MIS- (metal–insulator–semiconductor) or MS- (metal–semiconductor) sensors. The internal barrier inside the sensors separates ground state carriers from excited carriers. It is an open question, whether electrochemical reactions on metal surfaces also evoke hot charge carriers. We study the electrochemical deposition of hydrogen (via Hupd) on platinum and the oxidation of platinum in sulfuric and hydrochloric solution. As sensors Pt–TaOx–Ta, Pt–SiOx–Si and Pt–Si-sensors were used with 10-30 nm thick Pt films. By electrochemical cyclovoltametry and simultaneous recording of the current at the tantalum or silicon back electrode it is possible to detect voids (down to a fraction of 10−3) in the thin platinum film. 30 nm thick platinum films were found to cover the underlying layer completely. In this case the devices can be used to monitor deviations from the electronic equilibrium since excited carriers cause a device current through the internal barrier. Deviations from the electronic ground state were found in the case of the Hupd formation.