利用掃描穿隧能譜術研究界面對穿透共振的影響

Abstract

在量子力學中，對於一個一維的位能井問題。若入射粒子的能量高於真空能階，則粒子有可能以1 的機率穿透這個位能井。這個現象稱為「穿透共振」。在我們的實驗裡，我們在超高真空的環境下使用掃描穿隧能譜術在不同的金屬基板上鍍上銀薄膜來量測此種現象。我們一共在三種不同的基材上鍍上銀薄膜，分別為 金(111)，銅(100)和鈀(111)。其中在銅(100)和鈀(111)上鍍銀的系統有發現到穿透共振的現象，而這個現象在金(111)上並未發現。在發現到穿透共振的系統中，我們觀察到穿透共振隨著厚度相依的現象，並且也檢驗了穿透共振將其後的駐波態推往高能階的現象。而是否會產生穿透共振的現象的機制，和界面的影響與基材的電子結構有相當大的關係。

In quantum mechanics, when the free particle, e.g. electron, impinges on a one dimensional quantum well, the particle can penetrate through the well with probability 1 at some specific energy. This quantum phenomenon is called the transmission resonance, and can be observed using scanning tunneling spectroscopy for some thin metal films. We deposit Ag to form films on three different substrates, which are Cu(100), Pd(111), and Au(111), for studying the interface effect on transmission resonance. Our results demonstrate that the transmission resonance appears in the Ag/Cu(100) and Ag/Pd(111) systems but disappears in the Ag/Au(111) system. The mechanisms behind these results are the interface sharpness and the electronic structures of the substrates. The thickness dependence of transmission resonances was observed, and it was also confirmed that transmission resonances push standing wave states behind them to higher energy level.