Electrical conduction and metal-insulator transition of indium nanowires on Si(111)
Electrical conduction and metal-insulator transition of indium nanowires on Si(111)
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Si(111)上铟纳米线的导电和金属-绝缘体转变
DOI：
10.1103/physrevb.95.195409
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发表时间：
2017
影响因子：
3.7
通讯作者：
T. Aruga
中科院分区：
文献类型：
--
作者：
S. Hatta;T. Noma;H. Okuyama;T. Aruga
用四探针电导法研究了铟纳米线在Si(111)表面的金属-绝缘体(MI)转变。冷却后，具有金属电子带的高温相的片状电导率与Mott的可变范围跳跃电导的定量结果一致，呈现出逐渐下降的趋势。在进一步冷却时，电导率在120K时急剧下降，表明其转变为绝缘相。从65K开始加热的电导率在降温过程中没有出现曲线，而是出现了宽度为8K的热滞。观察到的磁滞与以前的电子衍射实验相一致，表明MI转变是一级的。进一步发现，与通常在一级相变中观察到的过热行为不同，加热时的相变从下面开始，同时总是观察到过冷现象。这表明只有在加热过程中才有特定的非均相成核过程。结果表明，这是由于磁区边界附近纳米线的失稳所致。在具有高台阶密度的衬底上观察到的转变温度显著降低，证实了这一点。
We have studied the metal-insulator (MI) transition of indium nanowires on the Si(111) surface by electrical conductivity measurements with a four-point probe. Upon cooling, the sheet conductivity of the high-temperaturephase, which is known to have metallic electron bands, exhibited a gradual decrease in quantitative agreement with the Mott's variable range hopping conduction. Upon further cooling, the conductivity exhibited a sharp drop at 120 K, indicating the transition into the insulatingphase. The conductivity upon heating from 65 K did not trace the curve during cooling but showed a thermal hysteresis with a width of 8 K. The observation of the hysteresis agrees with the previous electron diffraction experiments, showing that the MI transition is first order. It was further found that, instead of the superheating behavior usually observed in first-order transitions, the transition upon heating starts below, while the supercooling is always observed. This indicates a specific heterogeneous nucleation process only during heating. It is suggested that this is due to the destabilization of the nanowires near the domain boundaries. This is corroborated by the significant decrease of the transition temperature observed on a substrate with a high step density.