No abstract

We report on the formation of lobe-lobe (bi-lobed) Au-Ge nanostructures under ultra high vacuum (UHV) conditions (≈3× 10 -10 mbar) on clean Si(100) surfaces. For this study, ≈2.0 nm thick Au samples were grown on the substrate surface by molecular beam epitaxy (MBE). Thermal annealing was carried out inside the UHV chamber at temperature ≈500°C and following this, nearly squareshaped Au x Si 1-x nano structures of average length ≈ 48 nm were formed. A ≈2 nm Ge film was further deposited on the above surface while the substrate was kept at a temperature of ≈500°C.Well ordered Au-Ge nanostructures where Au and Ge residing side by side (lobe-lobe structures) were formed. In our systematic studies, we show that, gold-silicide nanoalloy formation at the substrate (Si) surface is necessary for forming phase separated Au-Ge bilobed nanostructures.Electron microscopy (TEM, STEM-EDS, SEM) studies were carried out to determine the structure of Au -Ge nano systems. Rutherford backscattering Spectrometry measurements show gold interdiffusion into substrate while it is absent for Ge.. PACS: 81.15. Hi, 64.75.St, 81.15.Aa