Surface morphology and electronic structure of Ge/Si(1 1 1) 7×7 system

A Ge film ~6 ml thick was grown on (7×7) reconstructed Si(1 1 1) substrate at room temperature as well as at elevated substrate temperature, viz. 450 and 550°C. The changes in electronic structure were studied in situ by photoelectron spectroscopy using synchrotron radiation as well as helium lamp. The surface morphology was studied ex situ by using atomic force microscopy. The growth of Ge on Si(1 1 1) 7×7 was found to be highly disordered at room temperature. At 450°C, it showed columnar growth of Ge, with a peculiar double column structure. The increase in the temperature from 450 to 550°C changes the structure and composition of islands. At 550°C, triangular pyramid shaped islands of uniform size are formed