Semiconductor on metal adsorption: Ge tetramers on the Ag(001) surface

This paper presents an experimental study of the first stages of the growth of a semiconductor (Ge) deposited at room temperature on an oriented metal lic surface (Ag(001)). It is achieved by using scanning tunneling microscop y (STM), Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and photoelectron spectroscopy (PES). This work shows particular st able entities of four Ge atoms (tetramers) which are observed as early as t he first stages of growth (0.1 ML) in coexistence with isolated Ge atoms in serted in substitutional sites of the Ag top layer. These tetramers order i n a p(2 root 2 x 4 root 2)R45 degrees superstructure at half monolayer (0.5 Ge ML). Beyond this coverage, the adlayer disorders. The PES study reveals the metallic character of the Ge adlayer at least up to 0.5 ML. (C) 2000 E lsevier Science B.V. All rights reserved.