Acetylene molecules on the Si(001) surface: room-temperature adsorption and structural modification upon annealing

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• 作者：Kim ; Wondong ; Kim ; Hanchul ; Lee ; Geunseop ; Chung ; Jaegwan ; You ; Sang-Yong ; Hong ; Young-Kyu ; Koo ; Ja-Yong
• 关键词：Scanning tunneling microscopy ; Ab initio quantum chemical methods and calculations ; Adsorption kinetics ; Surface relaxation and reconstruction ; Alkynes ; Silicon
• 刊名：Surface Science
• 出版年：2002
• 出版时间：August 10, 2002
• 年：2002
• 卷：514
• 期：1-3
• 页码：376-382
• 全文大小：228 K

文摘

Acetylene molecules adsorbed on the Si(001) surface are studied by scanning tunneling microscope and ab initio pseudopotential calculations. In case of room-temperature adsorption, there are basically two different kinds of di-σ bonding geometries at low coverage: (i) on-top and (ii) end-bridge di-σ configurations. The tetra-σ configurations are not found. Theoretical calculations show that the paired end-bridge configuration is dominant at high coverage. Based on these findings, we discuss the results at saturation coverage in the existing literature consistently. Subsequent annealing of the C₂H₂/Si(001) surface induces different C-induced surface structures depending on the acetylene coverage. At low coverage, parallel lines of dimer vacancies are observed. As the amount of the adsorbed acetylene increases, the c(4×4) ordered phase replaces the dimer vacancy line phase. Near saturation, clusters are formed and the surface becomes rough.