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HL: Halbleiterphysik

HL 10: Grenz- und Oberfl
ächen

HL 10.7: Talk

Monday, March 26, 2001, 17:00–17:15, S16

Structural and dynamical properties of Sn/Si multilayers — •B. Roldán Cuenya¹, W. Keune¹, M. Hu², W. Sturhahn², and M. Grimsditch² — ¹Laboratorium für Angewandte Physik, Gerhard-Mercator-Universität Duisburg, 47048 Duisburg — ²Argonne National Laboratory, Argonne, IL 60439, USA

The structure and lattice dynamics of Sn/a-Si multilayers grown at room temperature (RT) in ultrahigh vacuum on Si(111) have been studied by means of X-ray diffraction, Raman scattering, ¹¹⁹Sn Mössbauer spectroscopy, and ¹¹⁹Sn inelastic nuclear resonant scattering (INRS). The Sn layers in these multilayers were found to be in an amorphous pure α-like Sn phase up to a Sn thickness t_Sn of 10 Å. The formation of crystalline β-Sn was observed with increasing Sn thickness above 10 Å. The 10 Å α-like Sn layers remain stabilized at the Sn/Si interface at RT. The Si layers were also found to be amorphous. We have measured the Sn-projected vibrational density of states (DOS) of the Sn layers in the Sn(10 to 20 Å)/Si(20 to 50Å) multilayers by INRS, and obtained the Lamb-Mössbauer factor (f), mean kinetic energy per atom (T) and mean constant force (K). A 500 Å crystalline α-Sn film grown epitaxially on InSb(001) was used as reference (f=0.14 ± 0.02). An enhancement of the f value (f=0.21 ± 0.01) for the α-like Sn in the Sn(10 Å)/Si(20 to 50 Å) multilayer was observed. The high temperature stability of the interfacial α-like Sn layer (relative to bulk α-Sn) is discussed in terms of the vibrational entropy.

Supported by DFG/GRK 277/1-97 and Ke 273/17-1