Homogeneous surface iron silicide formation on Si(111): Thec(8×4)phase
Homogeneous surface iron silicide formation on Si(111): Thec(8×4)phase
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Si(111) 上形成均匀的表面硅化铁：Thec(8×4) 相
DOI：
10.1103/physrevb.68.125306
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发表时间：
2003
影响因子：
3.7
通讯作者：
U. Starke
中科院分区：
文献类型：
--
作者：
M. Krause;F. Blobner;L. Hammer;K. Heinz;U. Starke
用扫描隧道显微镜（STM）、低能电子衍射和俄歇电子能谱研究了Si（111）表面铁硅化物形成的早期阶段。虽然在亚单层区域中初始铁与Si（111）的相互作用引起非均匀的岛形核，但是在室温下沉积1.5单层（ML）铁并随后在550-600 °C下退火导致具有c（8×4）表面周期性的平坦且均匀的膜。这种c（8×4）表面重构与确定的膜厚度有关，因此似乎直接通过界面稳定。薄膜的端部是一层横向排列成（2×2）周期晶格的吸附原子。在负的针尖偏压下，STM图像显示出与c（8×4）超晶胞对应的较暗和较亮的吸附原子交替排列。虽然（2×2）-周期性吸附原子排列在宽温度范围（450-600°C）和较厚的膜中发展，但长程有序c（8×4）结构仅在1-2 ML Fe覆盖和约600°C高温退火后才能观察到。然后，单个c（8×4）畴可以延伸到数百纳米的直径。新相的原子结构可以从CsCl（B2）结构中推导出来，并在发展完整结构模型的过程中阐明了一些结构细节。
The early stages of iron silicide formation on Si(111) were studied by scanning tunneling microscopy (STM), low-energy electron diffraction, and Auger electron spectroscopy. While the initial iron interaction with Si(111)in the submonolayer regime gives rise to inhomogeneous island nucleation, deposition of 1.5 monolayers (ML) iron at room temperature and subsequent annealing at 550-600 °C leads to a flat and homogeneous film with c(8×4) surface periodicity. This c(8×4) surface reconstruction is linked to a definite film thickness and thus seems to be stabilized directly through the interface. The film is terminated by a layer of adatoms whose lateral positions form a (2×2) periodic lattice. At negative tip bias voltages, STM images show an alternating arrangement of darker and brighter adatoms corresponding to the c(8×4) supercell. While the (2×2)-periodic adatom arrangement develops in a wide temperature regime (450-600°C) and also for thicker films, the long range ordered c(8×4) structure can be observed only for 1-2 ML Fe coverage and after high temperature annealing at about 600°C. Then single c(8×4) domains can extend to diameters of several hundred nanometers. The atomic structure of the new phase can be derived from a CsCl (B2) structure, and a number of structural details are elucidated on the course towards the development of a complete structural model.