Introduction to Spectroscopic Ellipsometry of Thin Film Materials

Andrew T.S. Wee, DPhil, is Professor of Physics and Director of the Surface Science Laboratory at the National University of Singapore (NUS). His research is focused on surface and nanoscale science, scanning tunnelling microscopy, and synchrotron radiation studies of the molecule-substrate interface.Xinmao Yin, PhD, is Professor of Physics at the Shanghai University, China. His research is focused on quantum materials and broad energy range optical spectroscopic techniques. Chi Sin Tang is scientist at the Institute of Materials Research and Engineering, Agency for Science Technology and Research (A*STAR), Singapore. His research is focused on the electronic and optical properties of low-dimensional materials.

• Preface ix1 Spectroscopic Ellipsometry: Basic Principles 11.1 Spectroscopic Ellipsometry 11.1.1 p- and s-Polarized Lights and Fresnel Coefficients 21.1.2 Representation of Polarized Lights 31.2 Principles of Ellipsometric Measurements 51.2.1 Rotating-Analyzer Ellipsometer 61.3 Experimental Setup 71.3.1 VASE Spectroscopic Ellipsometer 81.3.2 IR-VASE Spectroscopic Ellipsometer 91.4 Spectroscopic Ellipsometry: General Profiles 101.5 Ellipsometric Data for Multilayered System 111.6 Dielectric Models 121.6.1 Drude Model 131.6.2 Lorentz Model 141.6.3 Drude–Lorentz Model 161.6.4 Sellmeier and Cauchy Models 171.7 Chapter Summary 18References 182 Strongly Correlated Systems: Cuprates and Manganites 192.1 Introduction 192.2 High-Transition-Temperature Superconducting Cuprates 192.2.1 The Crystalline Structure of Cuprates 202.2.1.1 The Structure of La1−xSrxCuO4 202.2.1.2 The Structure of YBa2Cu3O7−δ 202.2.1.3 The Structure of Nd2−xCexCuO4 212.2.2 The Electronic Structure of Cuprates 222.3 Colossal Magnetoresistance Manganites 262.3.1 Crystal Structure of La1−xSrxMnO3 262.3.2 The Electronic Structure and Magnetism of LSMO 262.3.3 Strong and Weak Correlations in Ambipolar Cuprate Thin-Film Systems 282.3.4 Samples 292.3.5 Spectroscopic Ellipsometry 312.4 Charge Localization in Cuprate Thin Film on Oxide Substrate 372.5 Plasmon and High-Energy Exciton Excitations in Cuprate Thin Films 402.5.1 Observation of the Low- and High-Energy Plasmons in LSCO/STO Film 402.5.2 Observation of the High-Energy Excitons in the LSCO/STO Film 432.6 Jahn–Teller Splitting Energy Controls the Phase Transition in Manganite Thin-Film Systems 45References 493 Two-Dimensional Transition Metal Dichalcogenides 593.1 Introduction 593.2 Crystal Structures of 2D-TMDs 593.2.1 1H-Phase 603.2.2 1T and 1T′ -Phase 613.2.3 1H–1T′ -Phase Energetics 613.2.4 Arising Electronic Structures 613.2.4.1 Indirect-to-Direct Bandgap Transition 613.2.4.2 Spin–Orbit Splitting 623.2.4.3 1T′ -Phase Electronic Band Structure 633.2.5 2D-TMD: Excitons 643.2.5.1 Excitons in 2D-TMDs 653.2.5.2 Excitons and Trions 673.2.6 Investigative Objectives for 2D-TMDs 673.3 Ellipsometry in Probing Structural Phase Transition and Electronic Structures Monolayer-MoS2 683.3.1 Experimental Results 703.3.1.1 Sample Preparation 703.3.1.2 Optical Features of Monolayer-MoS2 703.3.1.3 Inverted and Fundamental Gaps of 1T′ -Phase 2D-TMDs 713.3.2 Dynamics of 1H–1T′ -Phase Transition 723.3.2.1 First-Principle Study: Role of Substrates 723.3.3 Analyzing the 1H–1T′ -Phase Transition of MoS2/Cu 753.3.3.1 Optical Characterization of MoS2/Cu 753.3.3.2 Raman and PL Characterization 763.3.3.3 Photoemission Spectroscopic Characterization 773.3.4 1H–1T′ -Phase Transition of WSe2/Au 793.3.4.1 Optical Characterization of WSe2/Au 803.3.4.2 Photoluminescence and Photoemission Characterization of WSe2/Au 813.3.4.3 Phase Transition Yield of 2D-TMDs 843.3.5 Section Conclusion 853.4 Three-Dimensional Resonant Exciton in Monolayer-WSe2 873.4.1 Materials, Methods, and Results 883.4.1.1 Sample Growth 883.4.1.2 Optical Characterization of Monolayer-WSe2 893.4.1.3 Exciton Peaks: Temperature Dependence 923.4.1.4 Fitting Parameters of 𝜀2 Spectra 943.4.2 Effects of Temperature on SOC in 2D TMDs 953.4.3 High-Energy Photoluminescence Characterization 973.4.4 Power-Dependent Photoluminescence Spectroscopic Study 993.4.5 Computational Studies 993.4.5.1 High-Energy Resonant Exciton Demonstrated via GW–BSE Calculations 993.4.5.2 Comparison Between Wannier–Mott and Resonant Excitons 1003.4.5.3 Origin of Resonant Exciton: Band Structure Calculations Analysis 1013.4.6 3D-Features of Resonant Exciton in Monolayer-WSe2 and Thickness Dependence 1033.4.7 Estimating Exciton Binding Energy 1053.4.8 Section Summary 1053.5 Anisotropic Plasmon Excitations in Quasi-Metallic 2D-TMDs 1063.5.1 Anisotropic Plasmons in 1T′ -Phase 2D-TMDs 1073.5.1.1 Sample Preparation 1073.5.1.2 Detection of Plasmon in 1T′ -Phase WSe2/Au 1083.5.2 One-Dimensional Plasmon in 1T′ -Phase WSe2 1103.5.3 Detecting Plasmons in 1T′ -Phase MoS2/Au Monolayer 1123.5.4 Analyzing One-Dimensional Plasmon in 1T′ -Phase 2D-TMDs 1153.5.5 1H–1T′ -Phase Transition 1163.5.6 Section Conclusion 117References 1184 Single-Layer Graphene Systems 1314.1 Introduction 1314.2 Crystal and Electronic Structure of Graphene 1314.2.1 Electronic Band Structure of Graphene 1324.3 Optoelectronic Properties of Graphene 1344.4 Spectroscopic Ellipsometry Study of Graphene 1354.4.1 Measurement and Data Analysis of Graphene 1354.5 Resonant Excitons in Graphene 1374.6 Substrate-Induced Manipulation of Many-Body Effects 1384.7 Conclusion and Outlook 141References 1425 Nickelate Systems 1495.1 Introduction 1495.2 Crystal Structure 1495.3 Electronic Structures and Ni3d-Orbital Physics 1505.4 Phase Diagram and Metal–Insulator Transitions of RNiO3 Systems 1515.4.1 Magnetic Phases in RNiO3 Systems 1525.5 Optical Characterization via Spectroscopic Ellipsometry 1535.5.1 Effects of Epitaxial Effects on the Electronic Correlations of Nickelate Thin Films 1545.5.2 Long-Range Spin Ordering in Nickelate Thin Films 1555.6 Conclusion and Outlook 159References 1616 Future Development and Applications of Spectroscopic Ellipsometry 1676.1 Development of Mueller Matrix Imaging Techniques in Spectroscopic Ellipsometry 1676.2 In Situ Analysis of Langmuir Monolayers 1696.3 Emergent Properties at Two-Dimensional Interfaces 1706.4 Micro Devices and Integrated Circuits 1716.5 Metamaterial Research 1726.6 Organic Electronics 1726.7 Biological Materials and Medicines 1736.8 Anisotropic Materials 1736.9 Process Control Analysis 173References 174Index 181