Origin of metallicity in atomic Ag wires on Si(557)
Origin of metallicity in atomic Ag wires on Si(557)
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DOI：
10.1088/1367-2630/17/4/043062
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发表时间：
2015-04-29
影响因子：
3.3
通讯作者：
Pfnuer, H.
中科院分区：
文献类型：
--
作者：
Krieg, U.;Lichtenstein, T.;Pfnuer, H.
研究了在Si（557）表面自组装形成的Ag根3原子线的金属性。为此，我们结合了高分辨率电子能量损失谱与隧道显微镜。通过将在发生部分解吸的高温下退火的样品上的过量Ag覆盖范围扩展至0.6 ML，我们证明了（111）微阶上的Ag-根3 x根3 R30度有序原子线中的一维金属性仅源自超过（局部）单层覆盖的Ag原子，其被吸附并定域在Si（557）表面的高度台阶部分。因此，这些Ag原子充当原子尺度上的非本征掺杂剂，导致覆盖依赖的子带填充和增加作为掺杂浓度的函数的本地化。第二层晶格气体以及（111）阶台上的Ag岛被证明不是相关的掺杂剂。我们在一个改进的格子气模型中模拟了这种特殊的饱和行为，并证明了掺杂的制备依赖性饱和是由于高温处理引起的平均平台尺寸和台阶形貌的变化。
We investigated the metallicity of Ag-root 3 ordered atomic wires close to one monolayer (ML) coverage, which are formed on Si(557) via self assembly. For this purpose we combined high resolution electron energy loss spectroscopy with tunneling microscopy. By extending the excess Ag coverage up to 0.6 ML on samples annealed at high temperatures where partial desorption occurs, we demonstrate that one-dimensional metallicity in the Ag-root 3 x root 3 R30 degrees ordered atomic wires on the (111) mini-terraces originates only from Ag atoms in excess of (local) monolayer coverage, which are adsorbed and localized at the highly stepped parts of the Si(557) surface. Thus these Ag atoms act as extrinsic dopants on the atomic scale, causing coverage dependent subband filling and increasing localization as a function of doping concentration. The second layer lattice gas as well as Ag islands on the (111) terraces turn out not to be relevant as dopants. We simulated the peculiar saturation behavior within a modified lattice gas model and give evidence that the preparation dependent saturation of doping is due to changes of average terrace size and step morphology induced by high temperature treatment.