Growth mode and dissolution kinetics of germanium thin films on Ag(001) surface: an AES–LEED investigation

Abstract

This paper presents an experimental study by Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) of the growth and thermal behavior (dissolution kinetics isotherms) of a semiconductor (germanium) deposited on an oriented metallic surface [Ag(001)]. The growth mode of germanium on Ag(001) is studied at 100°C and reveals a nearly layer-by-layer type growth mode, up to six monolayers. In the initial stages of growth, a surface superstructure p(4 2 ×2 2 )R45° appears which remains up to about half a monolayer. Above this coverage the superstructure rapidly disappears and the surface becomes more and more disordered, as deduced from the fuzziness of the LEED diffraction spots. The dissolution kinetics isotherms of one monolayer of germanium are studied in the temperature range 250–320°C. Only the dissolutions at the highest temperature studied are total, the others stop at some surface concentration. At the lowest temperature it corresponds to the formation of the same p(4 2 ×2 2 )R45° superstructure. These unusual behaviors are interpreted in terms of local equilibrium in the surface selvedge and incoherent lattice relaxation at the semiconductor/metal interface.