Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 28: Postersitzung (Elektronische Struktur, Grenzfläche fest-flüssig, Halbleiteroberflächen und -grenzflächen, Magnetismus und Symposium SYXM, Methodisches, Nanostrukturen, Oberflächenreaktionen, Teilchen und Cluster, Zeitaufgelöste Spektroskopie)

O 28.8: Poster

Mittwoch, 10. März 2004, 16:00–19:00, Bereich C

Correlation of electronic transport and structural properties of Cs layers on Si(001) — •Hong Liu, A.A. Shklyaev, V. Zielasek, and H. Pfnür — Universität Hannover, Institut für Festkörperphysik, Appelstr. 2, 30167 Hannover

Combining LEED, EELS, and conductivity measurements we have studied the correlation of electronic transport with structural properties of Cs layers on Si(001). Depending on the substrate temperature T during Cs deposition we find three different growth regimes. Only for T<160 K we observe the growth of a continuous metallic Cs film consisting of three-dimensional islands on top of the first 2 monolayers. Between 170 K and room temperature a pseudomorphic wetting layer forms with a saturation coverage of 1-1.5 ML.

For Cs deposition at around 160 K we observe discontinuities of the surface conductivity at 0.5, 1, and 1.5 monolayer coverage, respectively. Those at 0.5 and 1 ML can be associated with transitions of the surface reconstruction from 3 × 4 to 3 × 2 and 3 × 2 to 2 × 1, respectively. Based on EELS data, electrical phase transitions (metal - semiconductor - metal) in the submonolayer coverage range have been reported by others [1]. While according to EELS the wetting layer should be metallic, conductivity measurements show that the electrical transport in the layer is activated. Refined models of the surface structure will be presented.

[1] Ki-Dong Lee and Jinwook Chung, Phys. Rev. B 55 (1997) 12906.