單根錫掺雜氧化銦奈米線中量子干涉傳輸之研究

Abstract

ITO近年來由於它的高透射率、低電阻率等優點，被廣泛運用在的液晶顯示器，觸控面板和太陽能電池中。也因為ITO對人類的科技有很大的貢獻，所以它的導電機制及各種特性值得被深入的研究。 我們量測一系列無序程度不同的奈米線，電子的相位破壞長度（□L）從弱局域效應對磁電阻的分析中取得，其值隨著溫度上升而漸漸縮短，當 □ L 跟樣品的直徑差不多的時候，弱局域效應便會由一維轉到三維。我們在較有序(室溫電阻率約200cm□□□)的樣品發現了很長的□L，從0.25 K到40 K約為520 nm到150 nm，在整個測量的溫區間都顯示出一維弱局域效應的行為。然而在較無序的樣品中(室溫電阻率約1000cm□□□)，我們得到的 □ L 在0.26 K約為200 nm，當溫度升高時， □ L 在約12 K的時候變得小於我們奈米線的直徑，弱局域效應也因此由一維轉到三維。值得一提的是，我們在兩個無序程度較高的奈米線中都看到了因無序造成的自旋-軌道交互作用，並且在低溫出現了反弱局域效應，這證實了ITO的相位破壞長度與自旋-軌道交互作用的強度可以藉由無序程度的改變而調控。

Due to its high optical transparency and low resistivity, ITO has been widely used in LCDs, touch panels and solar cells in the recent years. Because of its huge contribution to human’s technology, the conduction mechanisms and electrical properties of ITO deserve more in-depth studies. We have measured a series of ITO nanowires with different levels of disorder. The electron dephasing lengths, which decrease with increasing temperature, are extracted from weak-localization magnetoresistance measurements. When the dephasing length is close to the nanowire diameter, the weak-localization effect will cross over from being one-dimensional to being three-dimensional. In one low- resistivity (200 cm □ □ □ at 300 K) nanowire, a long dephasing length was observed, which varied from about 500 nm at 0.25 K to 150 nm at 40K. Therefore, the nanowire revealed one-dimensional behavior over the whole measurement temperature range. In one high-resistivity (1000 □□ □cm at 300 K) sample, we got a dephasing length of 200 nm at 0.26 K. When the temperature increased, □ L became smaller than the diameter of the sample, and hence a crossover from one-dimensional to iii three-dimensional weak-localization effect was observed. In particular, we found disorder-induced spin-orbit interaction in the high-resistivity sample. In this case, weak anti-localization occurred in the low temperature region. This result demonstrates that the dephasing length and the strength of spin-orbit interaction can be tuned by varying the level of disorder in ITO nanowires.