Advanced Characterization Techniques for Thin Film Solar Cells

The book focuses on advanced characterization methods for thin-film solar cells that have proven their relevance both for academic and corporate photovoltaic research and development. After an introduction to thin-film photovoltaics, highly experienced experts report on device and materials characterization methods such as electroluminescence analysis, capacitance spectroscopy, and various microscopy methods. In the final part of the book simulation techniques are presented which are used for ab-initio calculations of relevant semiconductors and for device simulations in 1D, 2D and 3D.

Building on a proven concept, this new edition also covers thermography, transient optoelectronic methods, and absorption and photocurrent spectroscopy.

Daniel Abou-Ras is senior scientist at the Helmholtz Center Berlin for Materials and Energy, Germany. He obtained his PhD at ETH Zurich, Switzerland. In 2005, he was awarded the MRS Graduate Student Gold Award at the MRS Spring Meeting. His research interests are correlative approaches in scanning as well as transmission electron microscopy, mainly applied on semiconductor devices.

Thomas Kirchartz is professor in the Department of Electrical Engineering and Information
Technology at the University Duisburg-Essen and head of the Division for Organic and Hybrid Solar Cells at the Institute of Energy and Climate Research 5 ? Photovoltaics at the Research Center Julich, Germany. Previously he was Junior Research Fellow in the Department of Physics at Imperial College London, UK. He obtained his degree in Electrical Engineering and Information Technology from the University of Stuttgart, Germany, in 2006 and his PhD from the RWTH Aachen, Germany, in 2009.

Uwe Rau is full professor at the Faculty Electrical Engineering and Computer Science of the RWTH Aachen, Germany, since 2007 and head of the Institute of Energy and Climate Research 5 ? Photovoltaics at the Research Center Julich, Germany. He obtained his PhD 1991 from the University Tubingen and was scientific group leader from 1995?2007 at the Universities of Bayreuth and Stuttgart.

PART I. Introduction

INTRODUCTION TO THIN-FILM PHOTOVOLTAICS
Introduction
The Photovoltaic Principle
Functional Layers in Thin-Film Solar Cells
Comjparison of Various Thin-Film Solar-Cell Types
Conclusions

PART II. Device Characterization

FUNDAMENTAL ELECTRICAL CHARACTERIZATIONS OF THIN-FILM SOLAR CELLS
Introduction
Current/Voltage Curves
Quantum-Efficiency Measurements

ELECTROLUMINESCENCE ANALYSIS OF SOLAR CELLS AND SOLAR MODULES
Introduction
Basics
Spectrally Resolved EL
Spatially Resolved EL of c-Si Solar Cells
EL Imaging of Thin-Film Solar Cells and Modules
Electromodulated Luminescence under Illumination

CAPACITANCE SPECTROSCOPY OF THIN-FILM SOLAR CELLS
Introduction
Admittance Basics
Sample Requirements
Instrumentation
CV Profiling and the Depletion Approximation
Admittance Response of Deep States
The Influence of Deep States on CV Profiles
Deep-Level Transient Spectroscopy
Admittance Spectroscopy
Drive-Level Capacitance Profiling
Photocapacitance
The Meyer-Neldel Rule
Spatial Inhomogeneities and Interface States
Metastability

TIME-OF-FLIGHT ANALYSIS
Introduction
Fundamentals of TOF Measurements
Experimental Details
Analysis of TOF Results

TRANSIENT OPTOELECTRONIC CHARACTERIZATION OF THIN-FILM SOLAR CELLS
Introduction
Measurement Setup
Charge Extraction and Transient Photovoltage
CE with Linearly Increased Voltage
Time-Delayed Collection Field Method

STEADY-STATE PHOTOCARRIER GRATING METHOD
Introduction
Basic Analysis of SSPG and Photocurrent Response
Experimental Setup
Data Analysis
Results
DOS Determination
Data Collection by Automization and Combination with other Experiments
Summary

PART III. Materials Characterization

ABSORPTION AND PHOTOCURRENT SPECTROSCOPY WITH HIGH DYNAMIC RANGE
Introduction
Photothermal Deflection Spectroscopy
Fourier Transform Photocurrent Spectroscopy

SPECTROSCOPIC ELLIPSOMETRY
Introduction
Theory
Ellipsometry Instrumentation
Data Analysis
Spectroscopic Ellipsometry forThin-Film Photovoltaics
Summary and Outlook

CHARACTERIZING THE LIGHT-TRAPPING PROPERTIES OF TEXTURED SURFACES WITH SCANNING NEAR-FIELD OPTICAL MICROSCOPY
Introduction
How Does a Scanning Near-Field Optical Microscope Work?
The Role of Evanescent Modes for Light Trapping
Analysis of Scanning Near-Field Optical Microscopy Images by Fast Fourier Transformation
Investigation of Individua lWaveguide Modes
Light Propagation inThin-Film Solar Cells Investigated with Dual-Probe SNOM
Conclusion

PHOTOLUMINESCENCE ANALYSIS OF THIN-FILM SOLAR CELLS
Introduction
Experimental Issues
Basic Transitions
Case Studies

ELECTRON-SPIN RESONANCE (ESR) IN HYDROGENATED AMORPHOUS SILICON (a-Si:H)
Introduction
Basics of ESR
How to Measure ESR
The g Tensor and Hyperfine Interaction in Disordered Solids
Discussion of Selected Results
Alternative ESR Detection
Concluding Remarks

SCANNING PROBE MICROSCOPY ON INORGANIC THIN FILMS FOR SOLAR CELLS
Introduction
Experimental Background
Selected Applications
Summary

ELECTRON MICROSCOPY ON THIN FILMS FOR SOLAR CELLS
Introduction
Scanning Electron Microscopy
Transmission Electron Microscopy
Sample Preparation Techniques

X-RAY AND NEUTRON DIFFRACTION ON MATERIALS FOR THIN-FILM SOLAR CELLS
Introduction
Diffraction of X-Rays and Neutron by Matter
Grazing Incidence X-Ray Diffraction (GIXRD)
Neutron Diffraction of Absorber Materials for Thin-Film Solar Cells
Anomalous Scattering of Synchrotron X-Rays

IN SITU REAL-TIME CHARACTERIZATION OF THIN-FILM GROWTH
Introduction
Real-Time In Situ Characterization Techniques for Thin-Film Growth
X-Ray Methods for Real-Time Growth Analysis
Light Scattering and Reflection
Summary

RAMAN-SPECTROSCOPY ON THIN FILMS FOR SOLAR CELLS
Introduction
Fundamentals of Raman Spectroscopy
Vibrational Modes in Crystalline Materials
Experimental Considerations
Characterization of Thin-Film Photovoltaic Materials
Conclusions

SOFT X-RAY AND ELECTRON SPECTROSCOPY: A UNIQUE "TOOL CHEST" TO CHARACTERIZE THE CHEMICAL AND ELECTRONIC PROPERTIES OF SURFACES AND INTERFACES
Introduction
Charact