Thallium overlayers on Si(111): Structures of a
Thallium overlayers on Si(111): Structures of a
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Si(111) 上的铊覆盖层：a 的结构
DOI：
10.1116/1.581871
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
F. Netzer
中科院分区：
文献类型：
--
作者：
L. Vitali;F. Leisenberger;M. Ramsey;F. Netzer
利用紫外光电子能谱、低能电子衍射（LEED）、俄歇电子能谱（AES）和扫描隧道显微镜（STM）研究了Si(111)7×7表面Tl复层的结构和生长。在低覆盖率时，Tl吸附几乎只发生在（7×7）单元电池的缺陷部分，并形成小的二维簇。随着Tl覆盖率的增加，整个表面被覆盖，而（7×7）表面的周期性保持不变，LEED和STM证明了这一点。在前2层单层（ML）沉积后，Tl原子的高迁移率导致了少量但较大的岛屿的凝结。在Tl的第二层表面，观察到一个有趣的明亮对比线网络，这似乎是由（7×7）衬底周期性引起的，这可能是由（7×7）单元胞边界介导的表面应变引起的。高温下Tl-Si（111）的表面相图包含1ml覆盖率下的（1×1）结构和近似（6×6）相。后者是由于（1×1） ML之上的第二个Tl层结构不相称。
The structure and growth of Tl overlayers on Si(111)7×7 surfaces have been investigated using ultraviolet photoelectron spectroscopy,low-energy electron diffraction(LEED),Auger electron spectroscopy(AES), and scanning tunneling microscopy(STM). At low coverages Tl adsorption occurs almost exclusively on the faulted half of the (7×7) unit cell and forms small, two-dimensional clusters. With increasing Tl coverage the whole surface becomes covered while the (7×7) surface periodicity is maintained as evidenced by LEED and STM. After deposition of the first 2 monolayers (ML) the high mobility of Tl adatoms leads to the condensation of few, but large islands. At the surface of the second monolayer of Tl an interesting network of bright contrast lines is observed, which appears to be induced by the (7×7) substrate periodicity lying two layers below and which may be caused by the surface strain mediated by the (7×7) unit cell boundaries. The surface phase diagram of Tl–Si(111) at elevated temperatures contains a (1×1) structure at 1 ML coverage and an approximate (6×6) phase. The latter is due to an incommensurate structure of the second Tl layer on top of the (1×1) ML.