Si(111)表面早期氧化与Si-O成键过程

INITIAL OXIDATION AND Si-O BONDING PROCESS ON Si(111) SURFACE

用光电子谱(XPS与UPS)和俄歇直读谱峰形分析研究了Si(111)早期氧化和Si-O成键过程。说明氧吸附早期存在“过氧基分子”和氧原子在Si原子上顶位吸附两种状态。随着氧暴置量增加,过氧基分子逐渐消失,而第二层硅原子的背键位置被氧原子占有,同时存在氧原子顶位吸附。氧化层大概有3～4个原子层(约4～5A),存在类SiO_2和类SiO_4的结构,Si3p-O2p和Si3s-O2p键对氧化层俄歇峰形贡献最大。硅氧化过程似乎首先Si3p-O2p成键,随后Si3s-O2p逐步成为次强化学键。

The initial oxidation and Si-O bonding process on Si(111) surface are investigated by photoemission spectra (XPSand UPS) and AES lineshape analysis. It is shown that both atomic oxigen and peroxy radical molecular states coexist onthe Si(111) surface in the early stage but the peroxy radical molecular state will gradually disappear as the backgroundpositions of the second layer of Si substrate are occupied by the oxygen atoms. And in the meanwhile,the oxygen atomsstand on the Si top sites. The thickness of the oxidized layer is only about 3 to 4 atomic layers (4 to 5 Angstroms) witha mixture of SiO_2-like and SiO_1-like structures. The chemical bonds Si3p-O2p and Si3s-O2p predominate the auger line-shape of the surface oxide layer. It seems that Si3p-O2p bond will first form and Si3s-O2p gradually becomes stronger inthe oxide layer.