次單層銀夾層對鎳在鍺(111)-c(2×8)表面上隨溫度變化的影響
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2013
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當表面形成三種複雜重構介面時，鍍上少量的鎳原子，以掃描穿隧顯微鏡觀察原子團在不同溫度下的成長變化。隨著溫度上升，表面上隨意分佈的鎳原子團逐漸聚集形成大島。這些大島具有特殊結構：7×7島、六角形和長條狀，其中只有7×7島是具有週期性結構的島。經過統計，分析鎳原子團喜愛站在銀/鍺(111)-(√3×√3)的基底上。
在實驗過程中，在低溫時銀不會讓鎳與基底鍺發生反應，充分發揮阻擋的效果， 但提高樣品溫度後出現與鎳鍺系統相同原子島，顯示銀無法完全阻止鎳與鍺形成合金。另外，能夠使在純基底上的鎳原子無法與鍺發生反應，顯示銀具有一種長距離作用力。
比較鈷銀鍺系統和鎳。這兩種皆會發生面積小的島消失，大面積的島逐漸增加，此現象稱Ostwald ripening。在鈷銀鍺的系統裡，比較介面對於鈷的束縛，(4 ×4)介面比(√3×√3)介面強，而且成核的鈷島會推開(4×4)基底上的銀原子，在其他區域形成更大片的(√3×√3)重構；在鎳銀鍺系統裡，原子團的體積會隨著溫度上升而增大，顯示鎳在各種基底上皆會與鍺形成合金，且鎳島會喜愛站在(√3×√3)重構。
Abstract We deposited 0.4 ML Ag atoms on clean Ge(111)-c(2x8) surfaces, annealed at 750K, and then prepared Ag/Ge(111) multiple interfaces. We could observe four kinds of reconstruction on Ag/Ge(111) multiple interfaces :Ge(111)-c(2x8), Ag/Ge(111)-(√3×√3), Ag/Ge(111)-(4×4) and Ag/Ge(111)- (3x1). In this thesis, we regarded Ag/Ge(111)-(3x1) surfaces as parts of Ag/Ge(111)-(4×4) surfaces. We deposited 0.2 ML Ni atoms on multiple interfaces, annealed the sample at different temperature, and observed the growth of Ni clusters on multi interface surfaces. In this system, there were three kinds of island : 7x7 periodic islands, hexagonal islands and long shaped islands. Specially, the 7x7 periodic islands were regular. We classified and compared the type of Ni-containing islands, discovered that there were same type of islands that appeared on Ni/Ag/Ge(111)-(√3×√3) and Ni/Ag/Ge(111) multiple interfaces, but it did not find on Ni/Ge(111)-c(2x8) multiple interfaces, even there were Ni/Ge(111)-c(2x8) surfaces in our system. Therefore, Ag atoms in multi-interface system produced some of influence. Observed the systems of Co/Ag/Ge(111) and Ni/Ag/Ge(111). We found that they had the same phenomenon in annealing process － Ostwald ripening. The difference between them was the periodic island. In addition, We knew that Co-containing islands trended to grow on Ag/Ge(111)-(4×4) surfaces. But in our experiment, Ni-containing islands trended to grow on Ag/Ge(111)-(√3×√3) surfaces by measuring the clusters of area, height and numbers.
Abstract We deposited 0.4 ML Ag atoms on clean Ge(111)-c(2x8) surfaces, annealed at 750K, and then prepared Ag/Ge(111) multiple interfaces. We could observe four kinds of reconstruction on Ag/Ge(111) multiple interfaces :Ge(111)-c(2x8), Ag/Ge(111)-(√3×√3), Ag/Ge(111)-(4×4) and Ag/Ge(111)- (3x1). In this thesis, we regarded Ag/Ge(111)-(3x1) surfaces as parts of Ag/Ge(111)-(4×4) surfaces. We deposited 0.2 ML Ni atoms on multiple interfaces, annealed the sample at different temperature, and observed the growth of Ni clusters on multi interface surfaces. In this system, there were three kinds of island : 7x7 periodic islands, hexagonal islands and long shaped islands. Specially, the 7x7 periodic islands were regular. We classified and compared the type of Ni-containing islands, discovered that there were same type of islands that appeared on Ni/Ag/Ge(111)-(√3×√3) and Ni/Ag/Ge(111) multiple interfaces, but it did not find on Ni/Ge(111)-c(2x8) multiple interfaces, even there were Ni/Ge(111)-c(2x8) surfaces in our system. Therefore, Ag atoms in multi-interface system produced some of influence. Observed the systems of Co/Ag/Ge(111) and Ni/Ag/Ge(111). We found that they had the same phenomenon in annealing process － Ostwald ripening. The difference between them was the periodic island. In addition, We knew that Co-containing islands trended to grow on Ag/Ge(111)-(4×4) surfaces. But in our experiment, Ni-containing islands trended to grow on Ag/Ge(111)-(√3×√3) surfaces by measuring the clusters of area, height and numbers.
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掃描穿隧顯微鏡, STM