Investigation of Subsurface Dopant-Induced Features on Si(100)-2x1:H Surface by Scanning Tunneling Microscopy

由於表面能態之消除，使氫鈍化之矽(100)-2x1表面下之摻雜得以被觀察。在本篇論文當中，表面下硼誘發於氫鈍化之矽(100)-2x1表面之特徵以超高真空顯微術觀察。對所有在本實驗所觀察到的硼誘發之表面特徵,可以藉著其形貌及振幅的不同而大略的區分不同的誘發特徵。這些硼誘發之表面特徵的差異是由於表面非等向結構所造成表面非等向的電子結構影響處在不同位置的硼摻雜所誘發之表面特徵的行為。更近一步分析於不同偏壓下特定表面特徵的延展行為發現該特徵局部非等向性的延展行為顯現表面非等向晶格結構確實影響摻雜誘發之特徵的行為。Hydrogen-passivated Si (100)-2x1 surface enables the observation of subsurface dopant because of elimination of surface states. In this thesis, boron-induced features on Si(100)-2x1:H surface are studied by ultrahigh vacuum scanning tunneling microscopy. For all the features we have observed, different types of boron-induced features can be roughly distinguished in terms of appearances and amplitudes. The divergence between these features are due to that surface anisotropic lattice structure contributing anisotropic electronic structure affects the behavior of these boron-induced features, induced by boron located in different sites. Furthermore, by analyzing the extension behavior of a specific boron-induced feature at different sample bias, the local anisotropic extension reflects that anisotropic surface lattice structure indeed influence the behavior of the boron-induced feature.Table of Contentsbstract cknowledgementsable of Contents hapter 1. Introduction 1hapter 2. Experimental principles 7.1 Principles of scanning tunneling microscopy (STM) 7.2 Local density of state (LDOS) 9.3 STM operating modes 10a) Constant current mode 10b) Constant height mode 11c) Current image tunneling spectroscopy (CITS) 12.4 Lattice structure of Silicon and Si(100)-2x1 reconstruction 13.5 Hydrogen-passivated Si (100)-2x1 surface 17.6 Tip-induced band bending effect 19hapter 3. Experimental Instruments and Procedures 21 3.1 Experimental Setup 21 3.2 Ultra-high-vacuum (UHV) System 22.3 Experimental procedures 25 3.3.1 Sample preparation 25 3.3.2 Hydrogen exposure 26 3.3.3 Hydrogen-cracking system 26hapter 4. Results and Discussion 27.1 Bare Si(100)-2x1 surface 27.2 Hydrogen-passivated Si(100)-2x1 surface 30.3 Subsurface dopant-induced features 32.4 Local anisotropic extension of subsurface boron-induced features on Si(100)-2x1:H surface 35.5 Analyses and comparison for three dopant-induced features 40.6 Conclusion 4