Heteroepitaxial growth of Ge films on the Si(100-2 x 1 surface

The initial stage of Ge heteroepitaxy on a Si(100)-2 x 1 surface has been investigated by low-energy electron diffraction (LEED) and Auger-electron spectroscopy (AES). The growth mode of the Ge films was studied by measuring the decrease in the Si(LVV) AES line at 92 eV with an increase in the Ge overlayer thickness. The Ge films deposited at room temperature exhibit layer-by-layer growth up to at least six monolayers. When the substrate is heated up to 350 C, the growth mode is of the Stranski-Krastanov type. The annealing behavior of the Ge films suggests that the bond strength between Ge and Si is stronger on Si(100) than on Si(111) surfaces. Thick Ge films deposited onto Si(100) surfaces held at 350 and 470 C display a sharp 2 x 1 LEED pattern and demonstrate single-crystal growth of a Ge(100) face on the Si(100) surface.