矽烯(Silicene)在近年一直都是二維材料研究的重點之一。結構與電子特性都與石墨烯接近，皆被預測為可研究量子自旋霍爾效應(QSH)的材料。目前矽烯只能以人造的方式磊晶成膜，大部分都是成長於金屬基板上。然而矽烯與金屬基板能帶的混成使得原本的電子能態特性也受到影響而無法觀測到。因此成長不受基板影響的矽烯仍是目前重要的課題。另一方面，二維材料異質結構在近年也引發了關注。二維材料的單層特性使異質結構有了垂直向或橫向兩種不同異質接面，兩種接面都能量測到有趣的物理性質。
本論文中，針對矽烯，選擇了相似的二維材料鍺烯(Germanene)來成長異質結構。希望藉由不同異質結構的成長，在垂直向接面量測到矽烯與鍺烯各自的固有電子能態，以及在橫向接面觀察到晶格不匹配所造成的應力如何影響結構介面。實驗中，以矽、鍺同時蒸鍍或是先後蒸鍍的方式來成長垂直或平面的矽烯-鍺烯異質結構。並使用掃描穿隧式顯微鏡(STM)來量測樣品。
為了成長矽烯-鍺烯異質接面，在實驗中使用了三種不同的金屬基板，並以分子束磊晶(MBE)的方式蒸鍍矽與鍺。在銀(111)面上，矽烯已經有了不少的研究結果。文中先針對多層矽/銀(111)的結構進行討論，氘原子的吸附產生的重構指向了多層矽為矽(111)薄膜而非多層矽烯。在單層矽烯/銀(111)面上蒸鍍則觀察到鍺原子的有序吸附行為，並沒有形成鍺烯於單層矽烯之上。在另外兩種基板鋁(111)與金(111)面上，沒有觀察到預期的蜂巢狀矽烯結構，在仔細檢視原子排列後得出矽在此兩基板上皆以表面合金的方式成膜。

Silicene, with the atomic and electronic structure akin to that of graphene, has attracted much interest in recent years. So far, silicene can only be synthesized artificially on a few substrates which are mostly metals. However, the electron band hybridization between silicene and substrates affects the fascinating electronic properties. Therefore growing near free-standing silicene is always one of the important issues. Recently, the heterostructure of two-dimensional (2D) materials induces much attention. The single layer structure leads to two kinds of heterojunction, vertical and lateral. Both of them provides interesting properties of physics.
In this thesis, with silicene as a basic material, the similar 2D material germanene is chosen to synthesize the heterostructure. The idea is trying to study the intrinsic electronic properties of silicene and germanene on the vertical heterojunction and the strained interface which is caused by the lattice mismatch on the lateral heterojunction. The growth of vertical and lateral silicene-germanene heterostructure was carried out by different growth conditions. Scanning tunneling microscopy (STM) is exploited to measure the surface.
To synthesize the heterostructure of silicene-germanene, three different substrates were exploited. There have been plenty of researches of the silicene/Ag(111) system. In the experiments, the structure of multilayer silicon on the Ag(111) was investigated. The reconstruction which was induced by the adsorption of atomic deuterium leads to the conclusion that the multilayer silicon on the Ag(111) surface is Si(111) film instead of multilayer silicene. On the monolayer silicene/Ag(111), the Ge only reveals ordered adsorption pattern and no germanene is observed. The deposition of Si on the other two substrates, Al(111) and Au(111), reveal ordered structure but not honeycomb. After detailed examination concludes these ordered structures are surface alloy.

Chapter 1 Introduction..........................................1
1.1 Graphene and Xenes.......................................1
1.2 Silicene.................................................4
1.3 Literature Review..........................................6
1.3.1 Silicon Growth at Two-Dimensional Limit on Ag(111).......6
1.3.2 Graphene−Silicon Heterostructures at the Two-Dimensional
Limit....................................................9
1.3.3 Compelling experimental evidence of a Dirac cone in the
electronic structure of a 2D Silicon layer..............14
Chapter 2 Experimental Apparatus and Methods...................19
2.1 Ultra-High Vacuum..........................................19
2.2 Scanning Tunneling Microscopy and Spectroscopy.............21
2.3 Experimental Details.......................................27
Chapter 3 Few-Layer Silicon Films on the Ag(111) Surface........29
3.1 Introduction of Multilayer Si/Ag(111)......................29
3.2 Results and Discussion.....................................31
3.3 Conclusions................................................39
Chapter 4 Ordered 2D Structure Formed upon the Molecular Beam Epitaxy Growth of Ge on the Silicene/Ag(111) Surface............40
4.1 Introduction...............................................40
4.2 Results and Discussion.....................................42
4.3 Conclusions................................................51
Chapter 5 Self-Assemble of Si-Al Surface Alloy.................52
5.1 Introduction...............................................52
5.2 Results and Discussion.....................................54
5.3 Conclusions................................................70
Chapter 6 Formation of Eutectic Alloy - Si Deposition on The Au(111) Surface.........................................................71
6.1 Introduction...............................................71
6.2 Results and Discussion.....................................73
6.3 Conclusions................................................84
Chapter 7 Conclusions...........................................85
7.1 Conclusions................................................85
7.2 Outlook and Future Works...................................87
References......................................................88
Appendix: Personal C.V..........................................93

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