Composition and Structure of Epitaxial CaF 2 Layers at the First Stages of Their Growth on Si(111)
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Composition and Structure of Epitaxial CaF2 Layers at the First Stages of Their Growth on Si(111) 1 1 R. Würz*, W. Bohne , W. Fuhs, J. Röhrich , M. Schmidt, A. Schöpke, and B. Selle Hahn-Meitner-Institut, Silizium-Photovoltaik, Kekuléstrasse 5, 12489 Berlin, GERMANY 1 Hahn-Meitner-Institut, Ionenstrahl-Labor, Glienicker Strasse 100, 14109 Berlin, GERMANY *Email: [email protected] ABSTRACT CaF2 films with thicknesses in the monolayer range (100 nm) films. The quality of these films was examined by RBS/Channeling measurements. For films grown at 650°C typical values of the minimum backscattering yield of χmin400°C. These results suggest an
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Figure 1. F/Ca concentration ratio of CaF2 films on Si(111) deposited at Ts=650°C and R=0.16 Å/s as a function of film thickness (a) and, for a thickness of 15 Å, as a function of TS (b). The lines are guides to the eye. The deviation of the uppermost RBS points in (a) is due to problems with background correction as discussed in [6]. onset of the interface reaction at about 450°C. This composition dependence is closely related with pronounced changes of the film structure. Figure 2 presents a sequence of AFM images of CaF2 films with a thickness of about 15 Å grown at increasing TS with a fixed rate of R=0.16 Å/s. For TS
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