Study of initial stages of Pb growth on the Si (7710) surface by the method of scanning tunneling spectroscopy
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Study of Initial Stages of Pb Growth on the Si (7710) Surface by the Method of Scanning Tunneling Spectroscopy R. A. Zhachuk, S. A. Teys, and B. Z. Olshanetsky^ Institute of Semiconductor Physics, Siberian Division, Russian Academy of Sciences, pr. Akademika Lavrentieva 13, Novosibirsk, 630090 Russia ^e-mail: [email protected] Submitted September 21, 2006; accepted for publication October 3, 2006
Abstract—Lead island growth on the Si (7710) surface containing steps three interplanar spacings d(111) in height and on the Si (111) singular surface was studied by scanning tunneling microscopy at room temperature. It is shown that triple steps control the shape and orientation of lead islands formed on the Si (7710) surface. It was found that preliminary storage of a silicon sample in a vacuum chamber affects the size and density of growing islands. According to the Auger electron spectroscopy data, this effect is caused by oxygen adsorption on the substrate surface from the residual atmosphere of the vacuum chamber. PACS numbers: 61.30.Hn, 61.46.Df, 68.37.Ef DOI: 10.1134/S1063782607050168
1. INTRODUCTION The study of the formation and quantum-size properties of nanoobjects such as nanowires and nanodots on the silicon surface attracts steady interest. One of the methods for fabricating ordered nanoobjects is selforganized growth using substrates with surfaces containing systems of regular steps [1–8]. Such surfaces are vicinal. Silicon surfaces inclined at small angles from the (111) plane in the [ 112 ] direction contain steps one and three interplanar spacings d(111) in height (triple steps) at room temperature [9–13]. The fraction of triple steps on the surface increases with the inclination angle to the (111) plane. A silicon surface consisting of regularly arranged steps three interplanar spacings in height, separated by (111) terraces one Si(111)-7 × 7 surface-structure cell in width is promising for fabricating nanostructures. Previously, it was believed that the orientation of this surface is (557) [9]; however, as was recently found, it is characterized by (7710) indices [14]. The period of the system of regular steps on the Si (7710) surface, which controls the size of formed nanostructures, is 5.33 nm [14]. Metal nanostructures with similar characteristic sizes can exhibit quantumsize effects at room temperature. The objective of this study was to gain data on the possibility of Pb nanostructure formation on the Si (7710) surface. Experiments were performed in ultrahigh vacuum using scanning tunneling microscopy (STM) and Auger electron spectroscopy (AES). The results obtained for the Si (7710) surface were com-
pared to results of similar experiments with the Si (111) singular face. 2. EXPERIMENTAL Experiments were carried out in two independent ultrahigh-vacuum chambers. One of them was equipped with devices for low-energy electron diffraction and AES. The residual gas pressure in this chamber was 1.6 × 10–10 Torr. The second chamber was equipped with STM in
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