AG ON SI(001)(2X1) FORMATION OF A 2X3 SUPERSTRUCTURE

We present scanning tunneling microscope (STM), low-energy electron di ffraction, Auger electron spectroscopy, and scanning electron microsco pe results on the growth of Ag on Si(001)(2X1). At room temperature Ag is adsorbed only at the silicon S(B) steps at first and preferentiall y forms dimers during further growth. At higher Ag coverages an inhomo geneous layer which does not cover the surface completely is formed an d Ag islands grow with Ag(111)\\Si(001). At a substrate temperature of 770 K Ag forms a homogeneous layer which covers the surface completel y. This layer shows a novel (2X3) reconstruction, which shows a strong bias polarity dependence in the STM images. On the top of this (2X3) layer, three-dimensional Ag islands grow with Ag(001)\\Si(001).