Constrained Self-organization of Nanostructures on Si(111)-7×7 Surfaces: From Domain Boundary to Surface Magic Cluster
Date Issued
2007
Date
2007
Author(s)
Hsuan-Hao Chang
DOI
en-US
Abstract
本研究結合實驗與理論計算方法，探討在受限條件下所產生的自組裝奈米結構。研究中，我們首次對存在於矽(111)-7×7重構表面的晶界的一維週期結構做了完整的觀察分析。同時對於表面奇異原子團也以繞射的方法首度決定其精確的原子結構。
矽(111)-7×7表面重構本身有著7×7的重構晶胞，晶域間的相位差也多達48種。不同的相位差對於晶界結構的生成提供了不同的受限環境，因此產生各式各樣的晶界結構。這部分的研究中，我們以掃瞄穿隧電子顯微鏡(STM)全面性地觀察分析存在於矽(111)-7×7表面上的晶界結構。對應於48種相位差而存在的晶界結構都詳細地以STM觀測並且建構出其原子的結構模型。進一步地分析結構模型，我們可歸納出晶界的基本構成單元，使我們對於此一表面的重構現象和機制有更深的瞭解。
吸附在矽(111)-7×7重構表面上的IIIB族金屬原子，因為晶格的限制和原子鍵結的特性，可生成尺寸和位置精準的奇異原子團二維晶體。我們利用掃瞄穿隧電子顯微鏡和第一原理理論計算對此奇異原子團進一步地研究。同時由於奇異原子團晶體的週期性和結構一致性，使我們得以利用低能電子繞射的方法，首度確定奇異原子團的精確原子結構。
This research focuses on the observation and structural analysis of self-organized nanostructures under constrained conditions by experimental methods combined with theoretical calculation. Main topics including domain boundaries and surface magic clusters fabricated on Si(111)-7×7 reconstructed surfaces are concerned. The kaleidoscopic appearances of domain boundaries were first completely revealed while the structure determination of surface magic clusters was first claimed experimentally.
The domain boundaries on Si(111)-7×7 reconstructed surfaces were completely surveyed over 48 kinds of phase shifts by scanning tunneling microscopy. By structural analysis, we conclude three levels of building blocks: geometric modules, variant dimer rows, and the adatoms, to decide the appearances of a domain boundary. The selections of these building blocks along with the structural information imply the general preference in energetical aspects on Si surfaces. This also helps realize the formation mechanism of the fundamental and complicated reconstructed surface.
The structure of a type of surface magic cluster is determined by a combination of scanning tunneling microscopy, density-functional calculations, and dynamical low energy electron diffraction. The diffraction method is applicable because these clusters created through hierarchical self-organization of Ga deposited onto a Si(111)-7×7 surface have identical size and structure and form an ordered array with exact translational symmetry. The unprecedented detailed structure information provided by the diffraction measurement is consistent with direct microscopic imaging and theoretical calculations.
Subjects
矽(111)
表面
奈米結構
自組裝
晶界
奇異原子團
Nanostructure
Si(111)
Self-organization
domain boundary
surface magic cluster
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-96-D89222023-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):65d70dbd40f66b7f367f79ee0bb3bf4b