| 摘要: | 在本研究中，我們使用膠帶劈裂以熔融法成長 Bi2Te3 晶體。透過低能量電子 繞射儀(Low Energy Electron Diffraction, LEED)、X 光光電子能譜術(X-ray Photoelectron Spectroscopy, XPS) 及 掃 描 穿 隧 顯 微 鏡 (Scanning Tunneling Microscope, STM)檢測 Bi2Te3 晶體在大氣、真空、氮氣及氧氣四種環境中劈裂的 表面改質現象。在真空環境中劈裂的 Bi2Te3 表面額外透過角解析光電子能譜術 (Angle-Resolved Photoelectron Spectroscopy, ARPES)檢測其能帶結構。在大氣環境 中劈裂的 Bi2Te3 表面一開始會受水氣侵蝕而產生 Bi 雙層，持續暴露則受到明顯 的氧化。在真空環境下劈裂的 Bi2Te3 表面並無觀察到任何改質現象，費米能階附 近呈現明顯的表面色散關係，顯示晶體表面仍維持高度有序且雜質與缺陷濃度低。因此在真空中以膠帶簡單劈裂Bi2Te3 的操作方式仍可維持樣品品質。在一大氣壓 的氮氣或氧氣背景中劈裂的表面會受到膠帶中汙染物的影響，存在些微水氣及碳 汙染，但未觀察到氧化現象。Bi2Te3 表面受到水氣侵蝕後可觀察到 Bi 雙層的 Bi4f 譜線及三重對稱的表面凹坑。表面進一步氧化後，有序結構受到破壞，並且無法 透過加熱恢復。
;In this study, we grew Bi2Te3 crystals using the melt-growth method and cleaved the surfaces of samples using tape. The surface modifications of the cleaved Bi2Te3 crystals were investigated in four different environments: atmospheric, vacuum, nitrogen, and oxygen, using Low Energy Electron Diffraction (LEED), X-ray Photoelectron Spectroscopy (XPS), and Scanning Tunneling Microscopy (STM). The Bi2Te3 samples cleaved in the vacuum environment were additionally characterized using Angle-Resolved Photoelectron Spectroscopy (ARPES) to examine their band structure. In the atmospheric environment, the cleaved Bi2Te3 surfaces initially experienced moisture erosion, leading to the formation of a Bi bilayer, which further underwent noticeable oxidation upon prolonged exposure. No surface modifications were observed on the Bi2Te3 surfaces cleaved in the vacuum environment, and the presence of a well-defined surface dispersion relation near the Fermi level indicated a highly ordered surface with low impurity and defect densities. Thus, the method of tape cleaving in vacuum could still maintain the sample quality. However, surfaces cleaved in 1atm of nitrogen or oxygen atmosphere were influenced by contaminants present in the tape, resulting in slight moisture and carbon contamination, while no oxidation was observed. After moisture erosion on the Bi2Te3 surface, Bi bilayer features in the Bi4f spectra of Bi2Te3 and some symmetric surface pits were observed. Further oxidation of the surface led to the destruction of the ordered structure, which could not be restored by heating. |
