以場離子顯微鏡進行覆鉑及覆鈀單原子級針尖的研究

Abstract

實驗藉由場離子顯微鏡，對電化學電鍍法所製備覆鉑及覆鈀單原子級針尖進行研究;而藉由成長完成的覆鉑及覆鈀單原子針，我們亦可轉換至場發射(FEM)模式，觀察[100]、[221]皺化的場發射影像，並獲得其對應的場離子影像。 我們發現部份成長單原子針的實驗中，無法獲得良好的金字塔結構，是由於鋪覆針尖的氧化層所造成的，而當針尖存在氧化層會造成金字塔的稜線較長、針尖遍佈雜點、[211]面的原子列間距較寬…等現象，而針對皺化程度不同的覆鈀鎢針進行曝氧，我們也可以觀察到相似的場離子影像。

In this study, we use field ion microscopy (FIM) to study and characterize Pt and Pd covered single atom tips (SATs) prepared with electrochemical deposition methods. Field emission patterns of (100) and (221) faceting were investigated by field emission microscopy (FEM) and the corresponding FIM patterns were obtained as well. We find that some Pd covered tungsten tips do not form good pyramidal structure probably due to an oxide layer at the tip surface. The FIM images of these tips resemble those images obtained for tungsten tips which have been annealed after oxygen exposure. There are several similar features, including longer ridge of the pyramids, higher defect density on the tip surfaces, and wider separation between atomic rows on (211) facets.