Si atom adsorption and diffusion on Si(110)-(1×1)and(2×1)

Abstract

We present a systematic periodic density-functional study of Si adsorption and diffusion on the Si(110)-$(1\ifmmode\times\else\texttimes\fi{}1)$ and $(2\ifmmode\times\else\texttimes\fi{}1)$ surface. The most stable binding configurations on both reconstructions are with a threefold coordinated adatom bridging the gap between two surface zigzag rows. Several of the structures can be stabilized by a lateral shift of the rows or by distortion of a row. The different structures can be identified from their density of states and scanning tunnel microscopy/current image tunneling spectroscopy (STM/CITS) images. Diffusion on the $(1\ifmmode\times\else\texttimes\fi{}1)$ surface is equally likely to proceed along and across zigzag rows. Along rows either simple diffusion or an exchange mechanism can occur, across rows only an exchange mechanism is possible. Diffusion on the $(2\ifmmode\times\else\texttimes\fi{}1)$ reconstruction is easier in the direction along rows than across and proceeds as simple diffusion, not exchange. The mobility of the adatom is higher on the $(2\ifmmode\times\else\texttimes\fi{}1)$ reconstruction.