Structure of Si atomic chains grown on the Si/Cu(110) c (2x2) surface alloy - art. no. 115414

The surface atomic structure of Si atomic chains grown on the Si/Cu(110) su rface alloy has been investigated by a combination of different experimenta l techniques. For Si coverages below 0.5 monolayers the low-energy electron diffraction (LEED) pattern shows a c(2X2) reconstruction, corresponding to the formation of a surface alloy. Upon further Si deposition, the LEED pat tern evolves toward a (2X2)-like structure with streaks along the [001] dir ection. Scanning tunneling microscopy (STM) images show the presence of lin ear atomic Si chains on top of the surface alloy layer. We present an atomi c model for the surface termination based on the STM images and on the main atomic directions of the (2 x 2)-like phase found by a simple analysis of the Si 2p full hemispherical x-ray photoelectron diffraction patterns. This model consists of linear atomic Si chains running along the [(1) under bar 10] surface direction formed on top of the surface alloy. The chains prese nt small (2 X 2) domains, which are not in phase with respect to each other . After heating the (2 X 2)-like phase up to 250 degreesC, a quasi-(3X4) st ructure is developed. This structure consists of similar chains exhibiting a different periodicity. Furthermore, we have used synchrotron radiation ph otoemission (x-ray and ultraviolet photoemission spectroscopy) to gather in formation about the electronic structure of the atomic chains.