Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 22: Organic-Inorganic Hybrid Systems and Organic Films
O 22.8: Poster
Monday, March 7, 2016, 18:15–20:30, Poster E
In-situ Kelvin Probe Study of the Work Function Evolution of Molybdenum Oxide Upon Gas Exposure — Sebastian Hietzschold1,2,3, Sebastian Beck1,3, •Stefan Brackmann1,2, Robert Lovrincic1,2, and Wolfgang Kowalsky1,2,3 — 1InnovationLab GmbH, Heidelberg, Germany — 2Institute for High Frequency Technology, TU Braunschweig, Braunschweig, Germany — 3Kirchhoff Institute for Physics, Heidelberg University, Heidelberg, Germany
The electronic properties of transition metal oxides are very sensitive to many processing parameters. It is still not completely understood if just oxidative adsorption at the surface or also diffusion into bulk vacancies is the reason for the observed changes in the effective surface potential. To clearly separate surface from bulk effects, we measure simultaneously the bulk conductivity (via current-voltage measurements) and work function (via Kelvin probe) of MoOx layers of varying thicknesses in-situ during gas exposure.
We find that shortly after evaporation of thin MoOx onto a silicon substrate with native oxide the work function starts at a maximum of 6.9 eV and then decreases monotonously down to 5.7 eV for exposure with pure oxygen and well below 5 eV for air exposure. We observe the saturation of the work function change even for low exposure. We also show that the gradient of this decrease as well as the saturation value of the decreased work function does not only depend on the total exposure but also on the time of the exposure, the base pressure and gas species supplied during the exposure.