Gold assisted molecular beam epitaxy of Ge nanostructures on Ge(100) Surface

We report on the gold assisted epitaxial growth of Ge nanostructures under ultra high vacuum (UHV) conditions (\approx3\times 10-10 mbar) on clean Ge (100) surfaces. For this study, \approx2.0 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 \approx500{\deg}C and following this, well ordered gold nanostructures placed on pedestal Ge were formed. A \approx 2 nm Ge film was further deposited on the above surface while the substrate was kept at a temperature of \approx 500{\deg}C. The height of the Ge (pedestal) underneath gold increased along with the formation of small Ge islands. The effect of substrate temperature and role of gold on the formation of above structures has been discussed in detail. Electron microscopy (TEM, SEM) studies were carried out to determine the structure of Au - Ge nano systems.