Heteroepitaxy of Si films on a Ge(100)-2×1 surface

Heteroepitaxial growth of thin Si films on a Ge(100)-2×1 surface has been studied by means of low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and low-energy electron loss spectroscopy (LEELS). When the substrate temperature Ts was maintained at room temperature, the intensity of the Ge AES signals decreased with an increase in the Si deposition thickness dSi, in accordance with a layer-by-layer growth of the Si films. No ordered LEED pattern was observed upon Si deposition and the LEELS spectra changed to that observed for a sputtered Si, thereby revealing the growth of amorphous Si films at Ts=RT. At a higher temperature, Ts=500 °C, the long-lived Ge AES signals and the energy-loss features associated with the Ge surface states as well as the Ge 3d derived loss peak suggested the formation of small islands via the Volmer–Weber growth mode. The LEELS spectrum at dSi =30 Å became almost the same as that observed for a clean Si(100)-2×1 surface, as an indication of a single-crystalline growth of Si films on a Ge(100) surface.