Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 40: Oxides and insulators
O 40.8: Talk
Thursday, March 30, 2006, 16:45–17:00, WIL A317
Photon emission from MgO thin films on Mo(100) — •Hadj-Mohamed Benia1, Stefania Benedetti2, Niklas Nilius1, and Hans-Joachim Freund1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6,14195 Berlin — 2Università di Modena e Reggio Emilia, Dipartimento di Fisica and INFM-CNR National Research Center on nanoStructures and bioSystem at Surface (S3), Via G. Campi 213/a, 41100 Modena, Italy
MgO is a prototype material which exhibits color centers (oxygen vacancies). Such centers dominate the optical properties as well as the catalytic behavior of the MgO surface. The aim of our experiment is to locally characterize the optical properties of surface color centers by employing STM in combination with photon emission spectroscopy (PSTM). For this purpose, we have grown MgO films on Mo(100) with varying thicknesses ranging from 2-10 monolayers. Depending on the MgO deposition temperature we have found different morphological and structural properties of the film by LEED and STM. The optical spectra are dominated by two emission peaks located at around 300 and 400 nm with intensities depending on preparation procedure and film thickness. We tentatively attribute these peaks to excitonic and defect-mediated recombination processes within the oxide film.