Initial stages of gold adsorption on silicon stepped surface at elevated temperatures
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nitial Stages of Gold Adsorption on Silicon Stepped Surface at Elevated Temperatures1 S. S. Kosolobova, Se Ahn Songb, E. E. Rodyakinaa, and A. V. Latysheva a
Institute of Semiconductor Physics, Russian Academy of Sciences, Siberian Branch, Novosibirsk, 630090 Russia b Samsung Advanced Institute of Technology, 440-600, POB 111 Suwon, Korea e-mail: [email protected] Submitted September 12, 2006; accepted for publication October 3, 2006
Abstract—Experimental study performed by ultrahigh vacuum reflection electron microscopy and atomic force microscopy reveals step instability on Si(111) surface during gold deposition at elevated temperatures (higher than 900°C). Our results show that transformations of regular atomic steps into the system of step bunches and vice versa depend on the gold coverage and direction of the electrical current heating the sample. The mechanism and conditions of the surface morphology transformations are discussed. PACS numbers: 61.72.Ji, 68.35.Fx, 68.37.-d DOI: 10.1134/S1063782607040173 1
1. INTRODUCTION
Understanding of the atomic processes that govern the surface morphology formation during sublimation, homo- and heteroepitaxial growth, and foreign atom adsorption is of great interest for surface science. In particular, atomic step behavior on a vicinal silicon surface has attracted much interest not only for obtaining new fundamental knowledge but also because it has great importance for device processing. A number of previous works [1–3] show that the direct electrical current used for sample heating leads to the redistribution of atomic steps on the silicon surface during sublimation. Under well-known experimental conditions, the system of regular atomic steps transforms into the system of step bunches which consist of a number of atomic steps located close to each other. While a lot of efforts are applied to understanding the many aspects of step bunching on a clean silicon surface, less is known about the influence of foreign atom deposition on the behavior of atomic steps at elevated temperatures. Experimental investigations [4] show that submonolayer gold adsorption on the Si(111) surface with low miscut angle initiates the changing of the distribution of atomic steps (regular steps step bunches). This step instability depends on the heating current direction, and is attributed to the change of adatom effective charge [5]. Changing of the surface morphology after gold deposition is also observed on the Si(111) surface with high miscut angle [6, 7], but with some differences. When the gold coverage increases, the critical one-step bunching is observed on the silicon surface irrespective of the direction of electric current. 1 The
text was submitted by the authors in English.
This step instability is considered to be a result of the changing of the properties of atomic steps. The physical origin of the redistribution of atomic steps during gold atom deposition is still controversial. In this paper, we have investigated the behavior of atomic steps on the Si(111) surface a
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