利用高階昆拉赫振盪量測鉛／矽（111）與鉛／鍺／矽（111）的功函數差異

Measurement of Work Function Difference between Pb/Si(111) and Pb/Ge/Si(111) by High-Order Gundlach Oscillation

黃旭昇(Hsu-Sheng Huang) ； 鄭文源(Wen-Yuan Chan) ； 蘇維彬(Wei-Bin Su)

《真空科技》 27卷2期 (2014/06) Pp. 23-30

摘要

利用表面活性劑介導的磊晶成長方法可將鍺薄膜成長於鉛單層薄膜和矽（111）基板之間。我們利用掃描穿隧顯微儀觀察高階昆拉赫振盪的尖峰特徵，進而量測鉛／矽和鉛／鍺／矽的功函數差異。由於矽和鍺的介電常數不同，因此在鉛／矽區域的穿隧電流必須高於在鉛／鍺／矽區域的穿隧電流2至3倍，才能在兩區域上建立相同的電場，進而以高階昆拉赫振盪量測出兩者的功函數差異為200 meV。我們相信這裡所發展的技術也可擴大應用於導體塊材的功函數量測。

關鍵字

昆拉赫振盪 ； 功函數量測 ； 表面活性劑介導的磊晶成長 ； 鉛單層薄膜

並列摘要

Ge films can be grown between the Pb overlayer and Si (111) substrate by the surfactant-mediated epitaxy. We detect the high-order Gundlach oscillation revealed in scanning tunneling microscopy (STM) to measure the work function difference between Pb/Si (111) and Pb/Ge/Si (111). Owing to different dielectric responses of Si and Ge, the tunneling current on Pb/Si has to be larger than that on Pb/Ge/Si by a factor of 2-3 to establish the same electric field in STM gap on both regions. This condition leads us to obtain a work function difference of 200 meV from observing Gundlach oscillation. It is believed that the method developed in this work can be extended to measure the surface work function difference of bulk conductors as well.

並列關鍵字

Gundlach oscillation ； Work function measurement ； Surfactant-mediated epitaxy growth ； Pb overlayer