Surface Science 433–435 (1999) 512–516 www.elsevier.nl/locate/susc Cu induced step bunching on a Si(111) vicinal surface studied by reflection electron microscopy Y. Takahashi, H. Minoda *, Y. Tanishiro, K. Yagi Department of Physics, Tokyo Institute of Technology, Oh-okayama, Meguro, Tokyo 152-8551, Japan Abstract Step bunching induced by Cu adsorption on a Si(111) vicinal surface was studied by reflection electron microscopy. A surface with a regular array of steps changes to wide (111) terraces and step bands due to the formation of the incommensurate (IC ) Cu-adsorbed structure on the Si(111) terraces. The maximum terrace width of the IC domains depends on the deposition conditions of Cu, and is wider at higher temperature and at lower deposition rate. (441) and (331) facets are formed on a vicinal Si(111) surface inclined towards the 112 direction, while no facet with definite index is noticed on a vicinal surface inclined towards the 110 direction. © 1999 Elsevier Science B.V. All rights reserved. Keywords: Cu; Si(111); Surface reconstruction; Surface steps 1. Introduction enable us to make a well-defined nanostructure without a lithographic technique. Metal adsorption induced step bunching and Metal adsorption induced step bunching and/or faceting on a vicinal Si surface is an attractive faceting in several systems has been studied by reflection electron microscopy (REM ) and spot phenomenon from both the fundamental and industrial points of view. Metal adsorption on a profile analyzing LEED (SPA-LEED) [1–10]. Energetics and/or kinetics in the system govern Si surface changes the surface reconstruction, and the change of surface reconstruction causes a the surface morphology after step bunching [2,3]. In the present paper a REM study of Cu adsorp- change in surface free energy. When a foreign metal is adsorbed on a Si vicinal surface, metal tion induced step bunching on a Si(111) vicinal surface is presented. adsorption induces surface reconstruction on a low index Si surface. The areas with the surface recon- struction expand by further adsorption due to the reduction of the surface energy of the reconstructed 2. Experimental procedure areas, and step bunching occurs at the same time. Thus, a surface with a regular array of steps The experiments were performed using an ultra- changes to a hill and valley structure. This may high vacuum electron microscope ( UHV-EM ) equipped with a Cu evaporator and a thickness * Corresponding author. Fax: +81-3-5734-2079. monitor. Si samples with a size of 7×1×0.4 mm3 E-mail address: hminoda@surface.phys.titech.ac.jp ( H. Minoda) were cut from a (111) wafer 1.4° off towards the 0039-6028/99/$ – see front matter © 1999 Elsevier Science B.V. All rights reserved. PII: S0039-6028(99)00464-1