次單層鈷在鍺(111)表面上隨溫度變化之研究

Abstract

本文主要是研究微量的Co 在Ge（111）上隨溫度變化。室溫下Co 就會與Ge 發生化合，而且隨溫度增高會出現各種不同現象，所以我們利用掃描穿隧顯微鏡去觀察實數空間下影像的變化。 加熱溫度400K∼965K 後，降回室溫去觀察，在不同的熱處理過程，影像出現一些特徵，對於這些明顯的特徵給予命名。除此之外，我們儘可能去分辨出特徵圖像的結構。 次亮點、小亮點則在每個溫度範圍皆存在，而六角形的小黑洞、具週 期性的島、黑線，分別在500K、700K、965K 接續出現，配合STM圖像的統計分析及相關論文，我們猜測次亮點為Co 堆積表面的三維島、小亮點為雜質，另外在不同溫度下出現的各種特徵，我們猜測六角形的小黑洞為Co5Ge7、週期性的島為錯位堆疊、黑線為表面上的Adatom 鍵結形成的Dimer-row。2 This thesis is a study about that effect of submonolayer Co on Ge（111）at different temperature. The Co and the Ge substrate will react to form Co-Ge compounds at room temperature. We observe many phenomena in real space by STM. The sample temperature varies from 400K to 965K, then cooled down to room temperature. The thermal effects are investigated from STM images. We find different characteristics in different heating processes, and try to distinguish them as possible as we can. STM images of the characteristics are called the meta-bright pot, the small bright pot, the hexagonal dark-pot, the periodic island and the dark-line. The first two have found in the STM images in all heating processes. The others appear at 500K, 700K, 965K, separately. Base on our experiments and related references, we infer that image of the meta-bright pot is similar to a Co 3-D island, the image of the small bright pot can be due to an impurity, the image of the hexagonal dark pot is an evidence of the formation of Co5Ge7, the image of the periodic island may be formed from a mismatch between Co and Ge lattice, and the dark-line image indicates a dimer-row occurs.