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arXiv 1711.03025cond-mat.mes-hall
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邻位Si(111)的原子分辨扫描力研究

Atomically resolved scanning force studies of vicinal Si(111)

Carmen Perez Leon, Holger Drees, Stefan Martin Wippermann, Michael Marz, Regina Hoffmann-Vogel

摘要:

有序台阶半导体表面由于其原子台阶的规则排列而吸引了强烈的关注,这使得它们成为一维系统(例如纳米线)生长的完美模板。利用调频扫描力显微镜(FM-SFM)和从头算方法研究了10度斜切的Si(111)面的原子结构。这种流行的阶梯式表面包含7 × 7重建的台阶,沿着Si(111)方向取向,由阶梯区域隔开。最近,基于扫描隧道显微镜(STM)图像的这三个步骤的原子结构一直是争论的主题。与STM不同,SFM的原子分辨能力来自针尖顶点与表面原子的化学键合。因此,对于半导体等具有波纹态密度的表面,SFM提供了STM的补充信息,并部分消除了形貌对电子结构的依赖性。我们的FM-SFM图像具有前所未有的空间分辨率的步骤确认模型的基础上(7 - 7 - 10)的表面取向,并揭示了该表面的结构细节。两种不同的FM-SFM对比与密度泛函理论计算一起解释了表面上缺陷、屈曲和填充不对称性的存在。我们的研究结果证明了adatoms,restatoms,和二聚体的邻位表面的结构的稳定之间的电荷转移的重要作用。

英文摘要:

Well-ordered stepped semiconductor surfaces attract intense attention owing to the regular arrangements of their atomic steps that makes them perfect templates for the growth of one- dimensional systems, e.g. nanowires. Here, we report on the atomic structure of the vicinal Si(111) surface with 10 degree miscut investigated by a joint frequency-modulation scanning force microscopy (FM-SFM) and ab initio approach. This popular stepped surface contains 7 x 7-reconstructed terraces oriented along the Si(111) direction, separated by a stepped region. Recently, the atomic structure of this triple step based on scanning tunneling microscopy (STM) images has been subject of debate. Unlike STM, SFM atomic resolution capability arises from chemical bonding of the tip apex with the surface atoms. Thus, for surfaces with a corrugated density of states such as semiconductors, SFM provides complementary information to STM and partially removes the dependency of the topography on the electronic structure. Our FM-SFM images with unprecedented spatial resolution on steps confirm the model based on a (7 7 10) orientation of the surface and reveal structural details of this surface. Two different FM-SFM contrasts together with density functional theory calculations explain the presence of defects, buckling and filling asymmetries on the surface. Our results evidence the important role of charge transfers between adatoms, restatoms, and dimers in the stabilisation of the structure of the vicinal surface.

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