Surface electronic properties of Na/Ge(111)-3x1

Abstract

The electronic properties of Na overlayers on Ge(111) are investigated using ultraviolet photoemission spectroscopy. Adsorption of Na atoms on Ge(111)-c(2 x 8) and Na/Ge(111)-3 x 1 surfaces does not change the semiconducting surface property. The Na/Ge(111)-3 x 1 surface is characterized using photoemission of adsorbed xenon. The local work function measurement shows that there are two different sites in (3 x 1) surface. One is close to Na atoms and its local work function is 0.48 eV lower than that of the other site. This Na-induced short range interacting area is about 33% of total surface, which indicates that the Na coverage of the (3 x 1) phase is about 1/3 ML.