Note: Intro -- Porous Silicon in Practice: Preparation, Characterization and Applications -- Contents -- Preface -- 1: Fundamentals of Porous Silicon Preparation -- 1.1 Introduction -- 1.2 Chemical Reactions Governing the Dissolution of Silicon -- 1.2.1 Silicon Oxides and Their Dissolution in HF -- 1.2.2 Silicon Oxides and Their Dissolution in Basic Media -- 1.2.3 Silicon Hydrides -- 1.3 Experimental Set-up and Terminology for Electrochemical Etching of Porous Silicon -- 1.3.1 Two-Electrode Cell -- 1.3.2 Three-Electrode Cell -- 1.4 Electrochemical Reactions in the Silicon System -- 1.4.1 Four-Electron Electrochemical Oxidation of Silicon -- 1.4.2 Two-Electron Electrochemical Oxidation of Silicon -- 1.4.3 Electropolishing -- 1.5 Density, Porosity, and Pore Size Definitions -- 1.6 Mechanisms of Electrochemical Dissolution and Pore Formation -- 1.6.1 Chemical Factors Controlling the Electrochemical Etch -- 1.6.2 Crystal Face Selectivity -- 1.6.3 Physical Factors Controlling the Electrochemical Etch -- 1.7 Resume of the Properties of Crystalline Silicon -- 1.7.1 Orientation -- 1.7.2 Band Structure -- 1.7.3 Electrons and Holes -- 1.7.4 Photoexcitation of Semiconductors -- 1.7.5 Dopants -- 1.7.6 Conductivity -- 1.7.7 Evolution of Energy Bands upon Immersion in an Electrolyte -- 1.7.8 Charge Transport at p-Type Si Liquid Junctions -- 1.7.9 Idealized Current-Voltage Curve at p-Type Liquid Junctions -- 1.7.10 Energetics at n-Type Si Liquid Junctions -- 1.7.11 Idealized Current-Voltage Curve at n-type Liquid Junctions -- 1.8 Choosing, Characterizing, and Preparing a Silicon Wafer -- 1.8.1 Measurement of Wafer Resistivity -- 1.8.2 Cleaving a Silicon Wafer -- 1.8.3 Determination of Carrier Type by the Hot-Probe Method -- 1.8.4 Ohmic Contacts -- 1.8.4.1 Making an Ohmic Contact by Metal Evaporation -- 1.8.4.2 Making an Ohmic Contact by Mechanical Abrasion. , References -- 2: Preparation of Micro-, Meso-, and Macro-Porous Silicon Layers -- 2.1 Etch Cell: Materials and Construction -- 2.2 Power Supply -- 2.3 Other Supplies -- 2.4 Safety Precautions and Handling of Waste -- 2.5 Preparing HF Electrolyte Solutions -- 2.6 Cleaning Wafers Prior to Etching -- 2.6.1 No Precleaning -- 2.6.2 Ultrasonic Cleaning -- 2.6.3 RCA Cleaning -- 2.6.4 Removal of a Sacrificial Porous Layer with Strong Base -- 2.7 Preparation of Microporous Silicon from a p-Type Wafer -- 2.8 Preparation of Mesoporous Silicon from a p++-Type Wafer -- 2.9 Preparation of Macroporous, Luminescent Porous Silicon from an n-Type Wafer (Frontside Illumination) -- 2.9.1 Power Supply Limitations -- 2.10 Preparation of Macroporous, Luminescent Porous Silicon from an n-Type Wafer (Back Side Illumination) -- 2.11 Preparation of Porous Silicon by Stain Etching -- 2.12 Preparation of Silicon Nanowire Arrays by Metal-Assisted Etching -- References -- 3: Preparation of Spatially Modulated Porous Silicon Layers -- 3.1 Time-Programmable Current Source -- 3.1.1 Time Resolution Issues -- 3.1.2 Etching with an Analog Source -- 3.1.3 Etching with a Digital Source -- 3.2 Pore Modulation in the z-Direction: Double Layer -- 3.3 Pore Modulation in the z-Direction: Rugate Filter -- 3.3.1 Tunability of the Rugate Spectral Peak Wavelength -- 3.3.2 Width of the Spectral Band -- 3.4 More Complicated Photonic Devices: Bragg Stacks, Microcavities, and Multi-Line Spectral Filters -- 3.4.1 Bragg Reflector -- 3.4.2 Multiple Spectral Peaks-"Spectral Barcodes" -- 3.5 Lateral Pore Gradients (in the x-y Plane) -- 3.6 Patterning in the x-y Plane Using Physical or Virtual Masks -- 3.6.1 Physical Masking Using Photoresists -- 3.6.2 Virtual Masking Using Photoelectrochemistry -- 3.7 Other Patterning Methods -- References -- 4: Freestanding Porous Silicon Films and Particles. , 4.1 Freestanding Films of Porous Silicon-"Lift-offs" -- 4.2 Micron-scale Particles of Porous Silicon by Ultrasonication of Lift-off Films -- 4.3 Core-Shell (Si/SiO2) Nanoparticles of Luminescent Porous Silicon by Ultrasonication -- References -- 5: Characterization of Porous Silicon -- 5.1 Gravimetric Determination of Porosity and Thickness -- 5.1.1 Errors and Limitations of the Gravimetric Method -- 5.2 Electron Microscopy and Scanned Probe Imaging Methods -- 5.2.1 Cross-Sectional Imaging -- 5.2.2 Plan-View (Top-Down) Imaging -- 5.3 Optical Reflectance Measurements -- 5.3.1 Instrumentation to Collect Reflectance Data -- 5.3.1.1 Reflectance Optics -- 5.3.1.2 Wavelength Calibration -- 5.3.2 Principles of Fabry-Pérot Interference -- 5.3.3 Analyzing Fabry-Pérot Interference Spectra by Fourier Transform: the RIFTS Method -- 5.3.3.1 Preparation of Spectrum for Fast Fourier Transform -- 5.3.3.2 Interpretation of the Fast Fourier Transform -- 5.3.4 Thickness and Porosity by the Spectroscopic Liquid Infiltration Method (SLIM) -- 5.3.4.1 Bruggeman Effective Medium Approximation -- 5.3.4.2 Determination of Thickness and Porosity by SLIM -- 5.3.4.3 Determination of Index of Refraction of the Porous Skeleton -- 5.3.4.4 Effect of Skeleton Index on Porosity Determined by SLIM -- 5.3.5 Comparison of Gravimetric Measurement with SLIM for Porosity and Thickness Determination -- 5.3.6 Analysis of Double-Layer Structures Using RIFTS -- 5.4 Porosity, Pore size, and Pore Size Distribution by Nitrogen Adsorption Analysis (BET, BJH, and BdB Methods) -- 5.5 Measurement of Steady-State Photoluminescence Spectra -- 5.5.1 Origin of Photoluminescence from Porous Silicon -- 5.5.1.1 Tunability of the Photoluminescence Spectrum -- 5.5.1.2 Mechanisms of Photoluminescence -- 5.5.2 Instrumentation to Acquire Steady-State Photoluminescence Spectra. , 5.6 Time-Resolved Photoluminescence Spectra -- 5.6.1 Long, Nonexponential Excited State Lifetimes -- 5.6.2 Influence of Surface Traps -- 5.7 Infrared Spectroscopy of Porous Silicon -- 5.7.1 Characteristic Group Frequencies for Porous Silicon -- 5.7.2 Measurement of FTIR Spectra of Porous Silicon -- 5.7.2.1 Transmission Mode Measurement Using the Standard Etch Cell -- References -- 6: Chemistry of Porous Silicon -- 6.1 Oxide-Forming Reactions of Porous Silicon -- 6.1.1 Temperature Dependence of Oxidation Using Gas-Phase Oxidants -- 6.1.2 Thermal (Air) Oxidation -- 6.1.3 Ozone Oxidation -- 6.1.4 High-Pressure Water Vapor Annealing -- 6.1.5 Oxidation in Aqueous Solutions -- 6.1.5.1 Aqueous Oxidation Induced by Cationic Surfactants -- 6.1.6 Electrochemical Oxidation in Aqueous Mineral Acids -- 6.1.7 Oxidation by Organic Species: Ketones, Aldehydes, Quinones, and Dimethylsulfoxide -- 6.1.8 Effect of Chemical Oxidation on Pore Morphology -- 6.2 Biological Implications of the Aqueous Chemistry of Porous Silicon -- 6.3 Formation of Silicon-Carbon Bonds -- 6.3.1 Thermal Hydrosilylation to Produce Si-C Bonds -- 6.3.2 Working with Air- and Water-Sensitive Compounds-Schlenk Line Manipulations -- 6.3.3 Classification of Surface Chemistry by Contact Angle -- 6.3.4 Microwave-Assisted Hydrosilylation to Produce Si-C Bonds -- 6.3.5 Chemical or Electrochemical Grafting to Produce Si-C Bonds -- 6.4 Thermal Carbonization Reactions -- 6.4.1 Thermal Degradation of Acetylene to form "Hydrocarbonized" Porous Silicon -- 6.4.2 Thermal Degradation of Polymers to Form "Carbonized" Porous Silicon -- 6.5 Conjugation of Biomolecules to Modified Porous Silicon -- 6.5.1 Carbodiimide Coupling Reagents -- 6.5.2 Attachment of PEG to Improve Biocompatibility -- 6.5.3 Biomodification of "Hydrocarbonized" Porous Silicon -- 6.5.4 Silanol-Based Coupling to Oxidized Porous Silicon Surfaces. , 6.6 Chemical Modification in Tandem with Etching -- 6.7 Metallization Reactions of Porous Silicon -- References -- Appendix A1. Etch Cell Engineering Diagrams and Schematics -- Standard or Small Etch Cell-Complete -- Standard Etch Cell Top Piece -- Small Etch Cell Top Piece -- Etch Cell Base (for Either Standard or Small Etch Cell) -- Large Etch Cell-Complete -- Large Etch Cell Top Piece -- Large Etch Cell Base -- Appendix A2. Safety Precautions When Working with Hydrofluoric Acid -- Hydrofluoric Acid Hazards -- First Aid Measures for HF Contact -- Note to Physician -- HF Antidote Gel -- Further Reading -- Appendix A3. Gas Dosing Cell Engineering Diagrams and Schematics -- Gas Dosing Cell Top Piece -- Gas Dosing Cell Middle Piece -- Gas Dosing Cell Bottom Piece -- Index.