Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 40: Halbleiteroberflächen und -grenzflächen

O 40.9: Vortrag

Donnerstag, 11. März 2004, 17:45–18:00, H45

Epitaxial Pr₂O₃ layers on Si (111) studied with LEED and surface XRD — •Nicole Jeutter, Zarife Özer, and Wolfgang Moritz — Section Crystallography, Department of Earth and Environmental Sciences, University of Munich

Pr₂O₃ is one of the few oxides which are stable in contact with Si at temperatures up to 1000 C. It has as high dielectric constant and a small lattice mismatch (under 0.3 %) to the Si (111) substrate lattice. We have grown Pr₂O₃ on the Si (111) surface by evaporation from a tungsten crucible loaded with Pr₆O₁₁. Measurements with LEED and XRD show that an epitaxial layer is formed at a substrate temperature of about 770 K with the (0001) plane of Pr₂O₃ parallel to the Si (111) surface. Subsequent annealing up to 1030 K for less than 2 minutes leads to a p(2x2) reconstruction of the Pr₂O₃ layer. Very weak reflections from a (√3x√3) structure appear after slow cooling to room temperature. A disordered (5x1) phase appears after desorption at temperatures above 1050 K. After further desorption the (7x7) structure of the Si (111) surface is recovered. First x-ray measurements show the orientation relative to the substrate. The interface consists of a Si-O-Pr bond with Pr above the T₄ site. No indication was found for an intermediate oxide layer. The thickness of the layer was 0.6 nm, corresponding to one unit cell of Pr₂O₃.