Alkali-metal-promoted oxidation of the Si(100)2 x 1 surface: Coverage dependence and nonlocality.
Alkali-metal-promoted oxidation of the Si(100)2 x 1 surface: Coverage dependence and nonlocality.
复制标题
碱金属促进的 Si(100)2 x 1 表面氧化：覆盖范围依赖性和非定域性。
DOI：
10.1103/physrevb.39.12775
复制
发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Hurych
中科院分区：
文献类型：
--
作者：
Starnberg;Soukiassian;Hurych
我们利用同步辐射核能级光导光谱研究了单层范围内碱金属（Na, Rb, Cs）的覆盖对Si (100) 2x1表面氧化的影响。通过比较不同Na和Cs覆盖层的氧化层厚度，我们发现要显著增强硅的氧化作用，需要超过<s:1> 0.5单层的覆盖层。这种阈值的存在表明，碱金属促进氧化的机制本质上是非局部的，这与最近的奥格电子能谱研究得出的结论形成强烈对比。我们还观察到，用Na生长的氧化物的厚度在退火后增加了（约50%），而用Cs生长的氧化物的厚度没有明显变化。使用Rb，我们得到中间结果。在所有的情况下，退火导致更高的氧化态。我们还报告了光谱随时间的变化，这在某种程度上类似于与样品退火相关的变化。
We have studied the effect of alkali-metal (Na, Rb, Cs) coverages in the monolayer range on the oxidation of the Si (100) 2× 1 surface by core-level photoemission spectroscopy using synchrotron radiation. By comparing oxide thicknesses obtained using various coverages of Na and Cs, we find that coverages in excess of≊ 0.5 monolayer are required to enhance significantly the oxidation of silicon. The existence of such a threshold demonstrates that the mechanism for alkali-metal-promoted oxidation is essentially nonlocal in nature, in strong contrast to the conclusions drawn in a recent Auger-electron-spectroscopy study. We also observe that the thickness of oxides grown with Na increases (by about 50%) upon annealing, while those grown with Cs do not change appreciably. Using Rb, we obtain intermediate results. In all cases, annealing results in higher-oxidation states. We also report spectral changes with time, which are to some extent analogous to those associated with annealing of the sample.