We found a two-dimensional, ordered surface alloy Cu(110)-c(2ϫ2)-Mn. The structure and composition of this surface compound were determined by quantitative low-energy electron-diffraction ͑LEED͒ analysis, which shows a large buckling in the surface alloy layer. The Mn atoms buckle outwards, and the Cu atoms inwards with a total buckling amplitude of 0.22 Å ͓17.2% of the ideal interlayer distance of Cu͑110͔͒. The results are compared to ab initio total-energy and force calculations. The first-principles structure optimizations are restricted to structural relaxations normal to surface, which is consistent with our LEED analysis. The theoretically determined buckling of 16.3% reproduces the experimental situation. The calculations predict a large magnetic moment for Mn of M ϭ3.82 B . A hypothetical nonmagnetic Cu(110)-c(2ϫ2)-Mn surface alloy shows no buckling (Ͻ1%), proving that the buckling is due to the magnetovolume effect of Mn. Investigation of the growth shows that, for substrate temperatures above 180 K, deposition of submonolayer amount of Mn leads to the formation of a c(2ϫ2) superstructure. A well-ordered structure at 0.5 ML was observed in the temperature range between 270 and 350 K. For films above 1 ML, a 16ϫ1 superstructure was observed giving evidence of a buckled, Mn-rich top layer. We also investigated the work-function change upon surface alloy formation. The ab initio calculations predict a work-function lowering of about 0.5 eV, and we identified the magnetism of Mn as the basic origin of the work-function change. The results are compared to the Cu(100)-c(2ϫ2)-Mn surface alloy.

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Microcrystalline silicon with properties relevant to highly efficient solar cells can be suc-cessfully prepared on glass for material characterization if a thin intrinsic ‘seed layer’ coating of the substrate is used. This is demonstrated by a detailed structure analysis on the base of Raman spectroscopy and photothermal deflection spectroscopy. The coating turns out to be crucial (1) for achieving a crystalline content as high as that of solar cell absorber material, (2) for creating a homogeneous structure in growth direction, and (3) for extending the range of deposition pa-rameters which lead to films with high crystallinity towards the regime of amorphous growth. Regarding electrical transport, ‘seed layer’ assisted growth results in a structure dependence of the dark conductivity which is very similar to that of material grown on bare glass. Regarding optical absorption spectra, residual interference fringes, which indicate structure non-uniformities, are clearly suppressed by means of ‘seed layers’. It is concluded that appropriate ‘seed layers’ play an important role for a comprehensive characterization and development of microcrystalline silicon layers for thin film devices.