鎳在鍺(111)-c(2x8)及銀/鍺(111)-(√3x√3)表面上的成長

Abstract

在室溫下蒸鍍少量鎳原子於鍺(111)-c(2x8)重構之上，並以掃描穿隧顯微鏡觀測其在不同加熱退火溫度下的改變。隨著加熱退火溫度的提升，原先分散於樣品之上的原子團聚集並形成了四種具有不同結構的原子島。當加熱退火溫度再度提升之後，表面上的原子島全數消失，只剩下極少量不規則的原子團，推測消失的原子島已鑽入基底之下。 在鍺(111)-c(2x8)重構之上蒸鍍銀並加熱退火使樣品表面轉變為銀/鍺(111)-(√3x√3)重構後，於室溫蒸鍍少量鎳原子並以掃描穿隧顯微鏡觀測其表面結構在不同加熱退火溫度下的改變並與鎳鍺系統的實驗結果比較，STM圖像顯示銀能夠保護基底不受鎳原子的破壞，然而在加熱退火溫度提升的過程中，原子島的總體積亦隨之上升，顯示銀並無法完全阻止鎳原子與基底形成合金。而在樣品表面上發現的三種不同結構的原子島中，其中一種未曾於鎳鍺系統中發現，代表銀在此系統中起了很大的作用。Depositing submonolayer of nickel atoms on the clean Ge (111)-c(2x8) substrate at room temperature, then investigating the difference of the surface in different annealing temperatures by scanning tunneling microscope. The clusters distributed on the surface form four kind islands when the annealing temperature rising. After annealing with higher temperature the islands disappear and we guess that the atoms diffuse into the substrate. We also do the experiment at Ag/Ge(111)-(√3x√3) surface, the scanning tunneling microscope images show that the silver buffer layer can prevent the formation of alloys, but the total volume of the clusters and islands on the surface increasing with the higher annealing temperature. That means silver can not prevent the formation of alloys at high temperature. After annealing, three kind islands appearing in different temperature region, only one of them can not be found in the Ni/Ge system. That means the silver atoms playe an important role in Ni/Ag/Ge system.