鎳、鈷薄膜在鈀�鎢(111)表面之吸附與縐化現象

Adsorption and faceting phenomenon of Ni, Co thin films on Pd / W(111) surface

忻佳緯(Jia-Wei Xin)

指導教授 ： 張嘉升

共同指導教授 ： 宋克嘉(Ker-Jar Song)

國立臺灣大學/理學院/物理研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.03168

摘要

在本研究中我們探討了鎳、鈷簿膜在鈀�鵭{112}縐化表面之熱穩定性與熱動力學特性。我們發現在熱退火後鎳和鈷都會與鈀在表面形成合金，而令人驚訝的是，其中鎳可以幫助鈀在鎢(111)表面引發縐化現象。另外11個熱脫附單層的鈷和1.2個熱脫附單層的鈀薄膜在熱退火後的低能量電子繞射圖形只顯示出相當微弱的{112}面繞射點，且沒有原先(111)面的繞射點。程控溫歐傑電子能譜顯示大於一個熱脫附單層的鈷、鎳薄膜在熱處理過程中均會形成三維島狀結構，表示這些較厚的膜在縐化表面並不是穩定的，而不能作為製備磁性單原子針尖的方法。但從這些實驗中我們發現小於一個熱脫附單層的鎳薄膜在（鎳，鈀）�鎢(111)表面具有良好的熱穩定性，這些系統仍有相當的潛力且值得在未來做更進一步的磁性量測。

關鍵字

表面科學 ； 縐化現象 ； 程控熱脫附 ； 低能量電子繞射 ； 歐傑電子能譜

並列摘要

We studied the thermal stability and thermodynamic properties of Ni, Co ultra thin films on faceted Pd/W{112} system. We found that both Ni and Co will form alloy with Pd upon annealing. To our surprise, the Ni is able to “help” Pd in inducing the faceting of W(111) surface. As for Co, after deposition and annealing of up to 11 TML of Co on 1.2 TML of Pd, faint LEED spots from {112} faceted surface always persist on top of a diffuse background, while no LEED spots from planar (111) surface is ever observed. Temperature programmed Auger spectra show thick films (>1TML) of Co and Ni tend to form 3D islands on the faceted surface upon annealing, indicating such uniform thick films on faceted Pd / W{112} system to be thermodynamically unstable and unlikely candidates for forming magnetic single atom tips. We do find that some of the thin (<1 TML) Ni films on faceted (Ni, Pd) / W{112} has good meta-stability. These are the systems in which there is still hope and warrants a MOKE measurement in the future.

並列關鍵字

surface science ； faceting phenomenon ； TPD ； LEED ； AES

參考文獻

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