PHYSICS OF SURFACES AND INTERFACES
CONTENTS CHAPTER 1 INTRODUCTION TO SURFACE PROCESSES 1 1 ELEMENTARY THERMODYNAMIC IDEAS OF SURFACES 1 1 1 THERMODYNAMIC POTENTIALS AND THE DIVIDING SURFACE 1 1 2 SURFACE TENSION AND SURFACE ENERGY 1 1 3 SURFACE ENERGY AND SURFACE STRESS 1 2 SURFACE ENERGIES AND THE WUL?THEOREM 1 2 1 GENERAL CONSIDERATIONS 1 2 2 THE TERRACE–LEDGE–KINK MODEL 1 2 3 WUL?CONSTRUCTION AND THE FORMS OF SMALL CRYSTALS 1 3 THERMODYNAMICS VERSUS KINETICS 1 3 1 THERMODYNAMICS OF THE VAPOR PRESSURE 1 3 2 THE KINETICS OF CRYSTAL GROWTH 1 4 INTRODUCTION TO SURFACE AND ADSORBATE RECONSTRUCTIONS 1 4 1 OVERVIEW 1 4 2 GENERAL COMMENTS AND NOTATION 1 4 3 EXAMPLES OF (131) STRUCTURES 1 4 4 SI(001) (231) AND RELATED SEMICONDUCTOR STRUCTURES 1 4 5 THE FAMOUS 737 STUCTURE OF SI(111) 1 4 6 VARIOUS ‘ROOT-THREE’ STRUCTURES 1 4 7 POLAR SEMICONDUCTORS, SUCH AS GAAS(111) 1 4 8 IONIC CRYSTAL STRUCTURES, SUCH AS NACL, CAF2, MGO OR ALUMINA 1 5 INTRODUCTION TO SURFACE ELECTRONICS 1 5 1 WORK FUNCTION, F 1 5 2 ELECTRON A?NITY, X, AND IONIZATION POTENTIAL F 1 5 3 SURFACE STATES AND RELATED IDEAS 1 5 4 SURFACE BRILLOUIN ZONE 1 5 5 BAND BENDING, DUE TO SURFACE STATES 1 5 6 THE IMAGE FORCE 1 5 7 SCREENING FURTHER READING FOR CHAPTER PROBLEMS FOR CHAPTER CHAPTER 2 SURFACES IN VACUUM: ULTRA-HIGH VACUUM TECHNIQUES AND PROCESSES 2 1 KINETIC THEORY CONCEPTS 2 1 1 ARRIVAL RATE OF ATOMS AT A SURFACE 2 1 2 THE MOLECULAR DENSITY, N 2 1 3 THE MEAN FREE PATH, L 2 1 4 THE MONOLAYER ARRIVAL TIME, T 2 2 VACUUM CONCEPTS 2 2 1 SYSTEM VOLUMES, LEAK RATES AND PUMPING SPEEDS 2 2 2 THE IDEA OF CONDUCTANCE 2 2 3 MEASUREMENT OF SYSTEM PRESSURE 2 3 UHV HARDWARE: PUMPS, TUBES, MATERIALS AND PRESSURE MEASUREMENT 2 3 1 INTRODUCTION: SOURCES OF INFORMATION 2 3 2 TYPES OF PUMP 2 3 3 CHAMBERS, TUBE AND ?ANGE SIZES 2 3 4 CHOICE OF MATERIALS 2 3 5 PRESSURE MEASUREMENT AND GAS COMPOSITION 2 4 SURFACE PREPARATION AND CLEANING PROCEDURES : IN SITU EXPERIMENTS 2 4 1 CLEANING AND SAMPLE PREPARATION 2 4 2 PROCEDURES FOR IN SITU EXPERIMENTS 2 4 3 SAMPLE TRANSFER DEVICES 2 4 4 FROM LABORATORY EXPERIMENTS TO PRODUCTION PROCESSES 2 5 THIN ?LM DEPOSITION PROCEDURES: SOURCES OF INFORMATION 2 5 1 HISTORICAL DESCRIPTIONS AND RECENT COMPILATIONS 2 5 2 THERMAL EVAPORATION AND THE UNIFORMITY OF DEPOSITS 2 5 3 MOLECULAR BEAM EPITAXY AND RELATED METHODS 2 5 4 SPUTTERING AND ION BEAM ASSISTED DEPOSITION 2 5 5 CHEMICAL VAPOR DEPOSITION TECHNIQUES CHAPTER 3 ELECTRON-BASED TECHNIQUES FOR EXAMINING SURFACE AND THIN ?LM PROCESSES 3 1 CLASSI?CATION OF SURFACE AND MICROSCOPY TECHNIQUES 3 1 1 SURFACE TECHNIQUES AS SCATTERING EXPERIMENTS 3 1 2 REASONS FOR SURFACE SENSITIVITY 3 1 3 MICROSCOPIC EXAMINATION OF SURFACES 3 1 4 ACRONYMS 3 2 DI?RACTION AND QUASI-ELASTIC SCATTERING TECHNIQUES 3 2 1 LEED 3 2 2 RHEED AND THEED 3 2 3 ELASTIC, QUASI-ELASTIC AND INELASTIC SCATTERING 3 3 INELASTIC SCATTERING TECHNIQUES: CHEMICAL AND ELECTRONIC STATE INFORMATION 3 3 1 ELECTRON SPECTROSCOPIC TECHNIQUES 3 3 2 PHOTOELECTRON SPECTROSCOPIES: XPS AND UPS 3 3 3 AUGER ELECTRON SPECTROSCOPY: ENERGIES AND ATOMIC PHYSICS 3 3 4 AES, XPS AND UPS IN SOLIDS AND AT SURFACES 3 4 QUANTI?CATION OF AUGER SPECTRA 3 4 1 GENERAL EQUATION DESCRIBING QUANTI?CATION 3 4 2 RATIO TECHNIQUES 3 5 MICROSCOPY-SPECTROSCOPY: SEM, SAM, SPM, ETC 3 5 1 SCANNING ELECTRON AND AUGER MICROSCOPY 3 5 2 AUGER AND IMAGE ANALYSIS OF ‘REAL WORLD’ SAMPLES 3 5 3 TOWARDS THE HIGHEST SPATIAL RESOLUTION: (A) SEM/STEM 3 5 4 TOWARDS THE HIGHEST SPATIAL RESOLUTION: (B) SCANNED PROBE MICROSCOPY-SPECTROSCOPY PROBLEMS, TALKS AND PROJECTS FOR CHAPTER CHAPTER 4 SURFACE PROCESSES IN ADSORPTION 4 1 CHEMI- AND PHYSISORPTION 4 2 STATISTICAL PHYSICS OF ADSORPTION AT LOW COVERAGE 4 2 1 GENERAL POINTS 4 2 2 LOCALIZED ADSORPTION: THE LANGMUIR ADSORPTION ISOTHERM 4 2 3 THE TWO-DIMENSIONAL ADSORBED GAS: HENRY LAW ADSORPTION 4 2 4 INTERACTIONS AND VIBRATIONS IN HIGHER DENSITY ADSORBATES 4 3 PHASE DIAGRAMS AND PHASE TRANSITIONS 4 3 1 ADSORPTION IN EQUILIBRIUM WITH THE GAS PHASE 4 3 2 ADSORPTION OUT OF EQUILIBRIUM WITH THE GAS PHASE 4 4 PHYSISORPTION: INTERATOMIC FORCES AND LATTICE DYNAMICAL MODELS 4 4 1 THERMODYNAMIC INFORMATION FROM SINGLE SURFACE TECHNIQUES 4 4 2 THE CRYSTALLOGRAPHY OF MONOLAYER SOLIDS 4 4 3 MELTING IN TWO DIMENSIONS 4 4 4 CONSTRUCTION AND UNDERSTANDING OF PHASE DIAGRAMS 4 5 CHEMISORPTION: QUANTUM MECHANICAL MODELS AND CHEMICAL PRACTICE 4 5 1 PHASES AND PHASE TRANSITIONS OF THE LATTICE GAS 4 5 2 THE NEWNS–ANDERSON MODEL AND BEYOND 4 5 3 CHEMISORPTION: THE ?RST STAGES OF OXIDATION 4 5 4 CHEMISORPTION AND CATALYSIS: MACROECONOMICS, MACROMOLECULES AND MICROSCOPY PROBLEMS AND PROJECTS FOR CHAPTER CHAPTER 5 SURFACE PROCESSES IN EPITAXIAL GROWTH 5 1 INTRODUCTION: GROWTH MODES AND NUCLEATION BARRIERS 5 1 1 WHY ARE WE STUDYING EPITAXIAL GROWTH? 5 1 2 SIMPLE MODELS – HOW FAR CAN WE GO? 5 1 3 GROWTH MODES AND ADSORPTION ISOTHERMS 5 1 4 NUCLEATION BARRIERS IN CLASSICAL AND ATOMISTIC MODELS 5 2 ATOMISTIC MODELS AND RATE EQUATIONS 5 2 1 RATE EQUATIONS, CONTROLLING ENERGIES, AND SIMULATIONS 5 2 2 ELEMENTS OF RATE EQUATION MODELS 5 2 3 REGIMES OF CONDENSATION 5 2 4 GENERAL EQUATIONS FOR THE MAXIMUM CLUSTER DENSITY 5 2 5 COMMENTS ON INDIVIDUAL TREATMENTS 5 3 METAL NUCLEATION AND GROWTH ON INSULATING SUBSTRATES 5 3 1 MICROSCOPY OF ISLAND GROWTH: METALS ON ALKALI HALIDES 5 3 2 METALS ON INSULATORS: CHECKS AND COMPLICATIONS 5 3 3 DEFECT-INDUCED NUCLEATION ON OXIDES AND ?UORIDES 5 4 METAL DEPOSITION STUDIED BY UHV MICROSCOPIES 5 4 1 IN SITU UHV SEM AND LEEM OF METALS ON METALS 5 4 2 FIM STUDIES OF SURFACE DI?USION ON METALS 5 4 3 ENERGIES FROM STM AND OTHER TECHNIQUES 5 5 STEPS, RIPENING AND INTERDI?USION 5 5 1 STEPS AS ONE-DIMENSIONAL SINKS 5 5 2 STEPS AS SOURCES: DI?USION AND OSTWALD RIPENING 5 5 3 INTERDI?USION IN MAGNETIC MULTILAYERS CHAPTER 6 ELECTRONIC STRUCTURE AND EMISSION PROCESSES AT METALLIC SURFACES 6 1 THE ELECTRON GAS: WORK FUNCTION, SURFACE STRUCTURE AND ENERGY 6 1 1 FREE ELECTRON MODELS AND DENSITY FUNCTIONALS 6 1 2 BEYOND FREE ELECTRONS: WORK FUNCTION, SURFACE STRUCTURE AND ENERGY 6 1 3 VALUES OF THE WORK FUNCTION 6 1 4 VALUES OF THE SURFACE ENERGY 6 2 ELECTRON EMISSION PROCESSES 6 2 1 THERMIONIC EMISSION 6 2 2 COLD ?ELD EMISSION 6 2 3 ADSORPTION AND DI?USION: FES, FEM AND THERMAL ?ELD EMITTERS 6 2 4 SECONDARY ELECTRON EMISSION 6 3 MAGNETISM AT SURFACES AND IN THIN ?LMS 6 3 1 SYMMETRY, SYMMETRY BREAKING AND PHASE TRANSITIONS 6 3 2 ANISOTROPIC INTERACTIONS IN 3D AND ‘2D’ MAGNETS 6 3 3 MAGNETIC SURFACE TECHNIQUES 6 3 4 THEORIES AND APPLICATIONS OF SURFACE MAGNETISM CHAPTER 7 SEMICONDUCTOR SURFACES AND INTERFACES 7 1 STRUCTURAL AND ELECTRONIC E?ECTS AT SEMICONDUCTOR SURFACES 7 1 1 BONDING IN DIAMOND, GRAPHITE, SI, GE, GAAS, ETC 7 1 2 SIMPLE CONCEPTS VERSUS DETAILED COMPUTATIONS 7 1 3 TIGHT-BINDING PSEUDOPOTENTIAL AND AB INITIO MODELS 7 2 CASE STUDIES OF RECONSTRUCTED SEMICONDUCTOR SURFACES 7 2 1 GAAS(110), A CHARGE-NEUTRAL SURFACE 7 2 2 GAAS(111), A POLAR SURFACE 7 2 3 SI AND GE(111): WHY ARE THEY SO DI?ERENT? 7 2 4 SI, GE AND GAAS(001), STEPS AND GROWTH 7 3 STRESSES AND STRAINS IN SEMICONDUCTOR ?LM GROWTH 7 3 1 THERMODYNAMIC AND ELASTICITY STUDIES OF SURFACES 7 3 2 GROWTH ON SI(001) 7 3 3 STRAINED LAYER EPITAXY: GE/SI(001) AND SI/GE(001) 7 3 4 GROWTH OF COMPOUND SEMICONDUCTORS CHAPTER 8 SURFACE PROCESSES IN THIN ?LM DEVICES 8 1 METALS AND OXIDES IN CONTACT WITH SEMICONDUCTORS 8 1 1 BAND BENDING AND RECTIFYING CONTACTS AT SEMICONDUCTOR SURFACES 8 1 2 SIMPLE MODELS OF THE DEPLETION REGION 8 1 3 TECHNIQUES FOR ANALYZING SEMICONDUCTOR INTERFACES 8 2 SEMICONDUCTOR HETEROJUNCTIONS AND DEVICES 8 2 1 ORIGINS OF SCHOTTKY BARRIER HEIGHTS 8 2 2 SEMICONDUCTOR HETEROSTRUCTURES AND BAND O?SETS 8 2 3 OPTO-ELECTRONIC DEVICES AND ‘BAND-GAP ENGINEERING’ 8 2 4 MODULATION AND D-DOPING, STRAINED LAYERS, QUANTUM WIRES AND DOTS 8 3 CONDUCTION PROCESSES IN THIN ?LM DEVICES 8 3 1 CONDUCTIVITY, RESISTIVITY AND THE RELAXATION TIME 8 3 2 SCATTERING AT SURFACES AND INTERFACES IN NANOSTRUCTURES 8 3 3 SPIN DEPENDENT SCATTERING AND MAGNETIC MULTILAYER DEVICES 8 4 CHEMICAL ROUTES TO MANUFACTURING 8 4 1 SYNTHETIC CHEMISTRY AND MANUFACTURING: THE CASE OF SI–GE–C 8 4 2 CHEMICAL ROUTES TO OPTO-ELECTRONICS AND/OR NANO-MAGNETICS 8 4 3 NANOTUBES AND THE FUTURE OF ?AT PANEL TV 8 4 4 COMBINATORIAL MATERIALS DEVELOPMENT AND ANALYSIS CHAPTER 9 POSTSCRIPT – WHERE DO WE GO FROM HERE? 9 1 ELECTROMIGRATION AND OTHER DEGRADATION E?ECTS IN NANOSTRUCTURES 9 2 WHAT DO THE VARIOUS DISCIPLINES BRING TO THE TABLE? 9 3 WHAT HAS BEEN LEFT OUT: FUTURE SOURCES OF INFORMATION