Anisotropic conductivity of the Si(111)4×1-In surface: Transport mechanism determined by the temperature dependence
Anisotropic conductivity of the Si(111)4×1-In surface: Transport mechanism determined by the temperature dependence
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DOI：
10.1103/physrevb.86.035325
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发表时间：
2012-07
影响因子：
3.7
通讯作者：
T. Uetake;T. Hirahara;Y. Ueda;N. Nagamura;R. Hobara;S. Hasegawa
中科院分区：
文献类型：
--
作者：
T. Uetake;T. Hirahara;Y. Ueda;N. Nagamura;R. Hobara;S. Hasegawa
用变温四探针扫描隧道显微镜测量了准一维金属表面Si（111）4× 1-In的各向异性电导率随温度的变化。利用正方形四探针法，我们成功地测量了平行于和垂直于In链的电导率作为温度的函数。结果表明，垂直于In链的电导率主要是衬底空间电荷层的电导率。此外，它被澄清，它强烈地依赖于基板闪蒸温度，这有时会阻碍在低温下的各向异性导电性。相反，平行于In链的电导率明显由表面态主导，并在110 K附近通过众所周知的4× 1至8× 2金属-绝缘体转变急剧下降。低温8× 2相的能隙高达1.250 meV，与之前的光电发射报告一致。
The temperature dependence of anisotropic conductivity of a quasi-one-dimensional metallic surface, Si(111)4× 1-In, was measured by a variable-temperature four-tip scanning tunneling microscope. Using the square four-point probe method, we succeeded in measuring the conductivity parallel and perpendicular to the In chains independently as a function of temperature. It was shown that the conductivity perpendicular to the In chains was mainly the conductivity of the space-charge layer of the substrate. Moreover, it was clarified that it strongly depends on the substrate flashing temperature and this sometimes hindered the anisotropic conductivity at low temperatures. In contrast, the conductivity parallel to In chains was clearly dominated by the surface states and decreased drastically around 110 K by the well-known 4× 1 to 8× 2 metal-insulator transition. The low temperature 8× 2 phase had an energy gap as large as ∼250 meV, consistent with previous photoemission reports.