Anisotropy in conductance of a quasi-one-dimensional metallic surface state measured by a square micro-four-point probe method
Anisotropy in conductance of a quasi-one-dimensional metallic surface state measured by a square micro-four-point probe method
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DOI：
10.1103/physrevlett.91.036805
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发表时间：
2003-07-18
影响因子：
8.6
通讯作者：
Hasegawa, S
中科院分区：
文献类型：
--
作者：
Kanagawa, T;Hobara, R;Hasegawa, S
我们设计了采用独立驱动的超高真空四尖扫描隧道显微镜的“方形微型四点探针法”，首次成功直接测量固体表面单原子层的各向异性电导率。单畴Si(111)4x1-In的准一维金属在室温下沿金属原子链(sigma(平行))的表面态电导为7.2(+/-0.6)x10(-4) S/square，比垂直方向(sigma(下))大约60倍。西格玛（平行）由具有各向异性表面态带色散的玻尔兹曼方程一致解释，而西格玛（底部）则由表面空间电荷层电导主导。
We have devised a "square micro-four-point probe method" using an independently driven ultrahigh-vacuum four-tip scanning tunneling microscope, and succeeded for the first time to directly measure anisotropic electrical conductance of a single-atomic layer on a solid surface. A quasi-one-dimensional metal of a single-domain Si(111)4x1-In had a surface-state conductance along the metallic atom chains (sigma(parallel to)) to be 7.2(+/-0.6)x10(-4) S/square at room temperature, which was larger than that in the perpendicular direction (sigma(bottom)) by similar to60 times. The sigma(parallel to) was consistently interpreted by a Boltzmann equation with the anisotropic surface-state band dispersion, while the sigma(bottom) was dominated by a surface-space-charge-layer conductance.