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O: Oberflächenphysik

O 7: Surface reactions I

O 7.4: Vortrag

Montag, 27. März 2006, 12:00–12:15, WIL C207

Influence of the isotope effect on chemicurrent detection — •David Krix, Ramona Nünthel, and Hermann Nienhaus — Experimental Physics, University of Duisburg-Essen, 47048 Duisburg, Germany

Hot charge carriers created in the exothermic reaction of atomic hydrogen and atomic deuterium with silver have been detected with the use of thin film Ag/p-Si(111) Schottky diodes. In thin film diodes excited holes can penetrate the metal film. If the holes are sufficiently energetic they can surpass the Schottky barrier and can be detected as a so called chemicurrent. The intensity of the chemicurrent is influenced by the transport process in the device. An exponential attenuation depending on the film thickness is observed. The experimental data show an isotope effect in the absolute intensity and attenuation length for deuterium vs. hydrogen. Chemicurrents as much as three times larger have been observed while exposing the devices to hydrogen than is the case with deuterium. The attenuation length of hot holes is found to be larger for hydrogen than for the deuterium case. The results are in agreement with theoretical predictions of electronic excitations by chemical reactions within the electronic friction model.