Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 13: Semiconductor substrates: Adsorption

O 13.8: Vortrag

Montag, 22. März 2010, 16:45–17:00, H34

SHG Spectroscopy of Potassium-Covered Si(100)(2x1) — •Dominic Gerlach, Björn Braunschweig, Gerhard Lilienkamp und Winfried Daum — Institute of Energy Research and Physical Technologies, TU Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld, Germany

Previous second-harmonic generation (SHG) studies of potassium-modified Si(100)/SiO2 interfaces have revealed dramatic changes in the SHG spectra due to the presence of potassium ions at the interface and electric-field-induced second-harmonic generation in the space charge region of the semiconductor [1]. Here we present results of SHG experiments with a saturation layer of potassium (0.5 monolayer) deposited on clean Si(100)(2x1) surfaces. The main effect of the potassium adlayer on the SHG spectrum is a spectrally flat background contribution similar to a metal surface. The strength of the surface E1 resonance of the undoped Si substrate is almost unaffected by the adlayer, although it appears strongly enhanced in the spectra by interference. An additional resonance at 3.9 eV is tentatively assigned to a surface plasmon excitation in the potassium layer. The SHG results are consistent with a metallic character of the adsorbed potassium.

[1] A. Rumpel et al., Phys. Rev. B 74 081303(R) (2006)