金ナノワイヤ構造・コンダクタンスの結晶方位依存性

抄録

A new transmission electron microscope-scanning tunneling microscope (TEM-STM) system was developed in order to simultaneously investigate structure and electrical conductance of gold contacts in ultra high-vacuum TEM. We found that the gold contact parallel to the [001] or [111] direction of both electrodes became short neck, while the contact parallel to the [110] direction, long nanowire. When the contact was short neck, the electrical conductance changed stepwise at some points and did discontinuously at the other parts. In this case, the broad conductance peaks appeared in the histogram. On the other hand, when the contact was long nanowire, the conductance changed stepwise and showed an integer times the quantum unit of conductance (G₀=2e²/h). In the histogram, the sharp peaks appeared. These experimental results were qualitatively in agreement with the previous theoretical results based on the mesoscopic theory.