Advanced Silicon Materials for Photovoltaic Applications

by Pizzini, Sergio

• ISBN13: 9780470661116
• ISBN10: 0470661119
• Edition: 1st
• Format: Hardcover
• Copyright: 2012-08-13
• Publisher: Wiley

Summary

Discusses the critical issue of how to obtain low-cost Silicon feedstocks for photovoltaic applications. Advanced Silicon Materials for Photovoltaic Applications: Covers the main issues concerning silicon for PV applications Deals with the fabrication processes of bulk and thin films silicon Addresses quality problems for low-cost feedstocks Discusses advanced chemical, structural, and electrical characterization techniques and computer modeling. Essential reading for academic researchers, industrial researchers and engineers in the field of photovoltaic devices, as well as PhD students.

Author Biography

Professor Sergio Pizzini is Chairman of NED SILICON SpA, a company which focuses on renewable energies. He is retired from the University of Milano-Bicocca, where he was a Professor of Physical Chemistry until 2008. He also held positions as Director of the Nanotechnology Science Doctorate and Director of the Doctorate School of the Faculty of Sciences at the University.
Professor Pizzini is currently a member of the Scientific Committee of the Solar Lab, a joint initiative of the University of Camerino, Department of Physics and of Renergies Italia, Spa. His scientific expertise spans from semiconductor physics and chemistry to surface defect science and silicon processes for photovoltaic uses. He is the author or co-author of four books as well as more than two hundred technical papers.

Table of Contents

Preface	p. xi
List of Contributors	p. xv
Silicon Science and Technology as the Background of the Current and Future Knowledge Society	p. 1
Introduction	p. 1
Silicon Birth from a Thermonuclear Nucleosynthetic Process	p. 2
Silicon Key Properties	p. 2
Chemical and Structural Properties	p. 2
Point Defects	p. 7
Radiation Damage and Radiation Hardness	p. 7
Advanced Silicon Applications	p. 9
Silicon Radiation Detectors	p. 9
Photovoltaic Cells for Space Vehicles and Satellite Applications	p. 11
Advanced Components Based on the Dislocation Luminescence in Silicon	p. 12
Silicon Nanostructures	p. 14
References	p. 15
Processes	p. 21
Introduction	p. 21
Gas-Phase Processes	p. 23
Preparation and Synthesis of Volatile Silicon Compounds	p. 23
Purification of Volatile Silicon Compounds	p. 30
Decomposition of Volatile Precursors to Elemental Silicon	p. 30
Most Common Reactors	p. 33
Recovery of By-Products	p. 38
Production of MG and UMG Silicon and Further Refining Up to Solar Grade by Chemical and Physical Processes	p. 40
MG Silicon Production	p. 42
Metallurgical Refining Processes	p. 47
Metal-Metal Extraction Processes	p. 52
Solid/Liquid Extraction Techniques	p. 54
Final Purification by Directional Solidification	p. 55
Solar-Grade Silicon Production from Pure Raw Materials or Via the Direct Route	p. 58
Fluoride Processes	p. 59
Silicon Production/Refining with High-Temperature Plasmochemical Processes	p. 61
Silicon Production Via Plasma Processes	p. 62
Silicon Refining Via Plasma Processes	p. 63
Electrochemical Processes: Production of Silicon Without Carbon as Reductant	p. 64
Conclusions	p. 68
Acknowledgements	p. 69
References	p. 70
Role of Impurities in Solar Silicon	p. 79
Introduction	p. 79
Sources and Refinements of Impurities	p. 79
Segregation of Impurities During Silicon Growth	p. 86
Equilibrium Segregation Coefficients	p. 86
Effective Segregation Coefficient	p. 87
Distribution of Impurities in Silicon Crystal Due to Segregation	p. 90
Role of Metallic Impurities	p. 92
Solubility and Diffusivity	p. 92
Impact on Charge-Carrier Recombination	p. 94
Modeling the Impact of Metallic Impurities on the Solar-Cell Performance	p. 96
Role of Dopants	p. 101
Carrier Mobilities in Compensated Silicon	p. 101
Recombination in Compensated Silicon	p. 103
Dopant-Related Recombination Centers	p. 105
Segregation Effects During Ingot Growth	p. 106
Detecting Dopants in Compensated Silicon	p. 107
Role of Light Elements	p. 108
Oxygen	p. 108
Carbon	p. 109
Nitrogen	p. 111
Germanium	p. 113
Arriving at Solar-Grade Silicon Feedstock Definitions	p. 114
References	p. 118
Gettering Processes and the Role of Extended Defects	p. 127
Introduction	p. 127
Properties of Transition-Metal Impurities in Silicon	p. 130
Solubility of Transition-Metal Impurities	p. 131
Diffusion of Transition-Metal Impurities	p. 136
Gettering Mechanisms and their Modeling	p. 139
Segregation Gettering	p. 140
Relaxation Gettering	p. 142
Injection Gettering	p. 142
Modeling of Gettering Kinetics	p. 143
Aluminum Gettering	p. 144
Phosphorus-Diffusion Gettering	p. 146
Boron-Diffusion Gettering	p. 149
Bulk Processes Affecting Gettering Efficiency and Kinetics	p. 150
Metal-Silicide Precipitates	p. 150
Dislocations	p. 154
Grain Boundaries	p. 167
Light-Element Impurities and Related Defects	p. 169
Gettering Strategies and Defect Engineering	p. 170
Conclusions	p. 173
Acknowledgements	p. 173
References	p. 174
Advanced Characterization Techniques	p. 189
Introduction	p. 189
Surface Photo voltage Spectroscopy	p. 190
The Basic Principles	p. 191
SPS Setup	p. 193
Surface Photovoltage Spectroscopy of Hydrogenated Nanocrystalline Silicon (nc-Si:H)	p. 194
Photocurrent Spectroscopy	p. 196
Basic Principles	p. 197
Spectral Photoconductivity Setup	p. 199
Application of Spectral Photoconductivity to Silicon and Silicon Devices	p. 201
Optical (Light) Beam Induced Current (OBIC or LBIC)	p. 202
Basic Principles of Optical Beam Induced Current Method	p. 202
Determination of the Electric Field and Depletion Region Extent in Particle Detectors by OBIC	p. 204
Scanning Probe Microscopy for the Nanoscale Electrical Characterization of Semiconductors for PV Applications	p. 207
Concluding Remarks	p. 210
References	p. 210
Advanced Analytical Techniques for Solar-Grade Feedstock	p. 215
Introduction	p. 215
Review of Analytical Techniques	p. 216
GDMS Analysis of PV Si	p. 222
SMS Analysis of PV Si	p. 223
Applications of SIMS and GDMS for PV Si Feedstock Studies	p. 227
Impurity Segregation in Directional Solidified (DS) Silicon Blocks	p. 227
Specification of [C], [O] and [N] in Solar-Grade Silicon Feedstock to be Used in DS Furnaces	p. 229
SIMS Capability for Reduced-Cost Measurement of [C, O, B, P]	p. 230
Problems in Conversion Between Resistivity and Dopant Concentration in Highly Compensated Silicon	p. 231
References	p. 232
Thin-Film Deposition Processes	p. 235
Introduction	p. 235
Deposition Techniques of Thin-Film Silicon	p. 235
Standard Radio-Frequency Plasma-Enhanced CVD	p. 236
Very High Frequency Plasma-Enhanced CVD	p. 236
Microwave Plasma-Enhanced CVD	p. 237
Expanded Thermal Plasma (ETP) Deposition	p. 237
Low-Energy Plasma-Enhanced PECVD	p. 238
Hot-Wire CVD	p. 238
In Situ Diagnosis of Growth Conditions	p. 239
Electrical: Current-Voltage (I-V) Probe	p. 239
Optical Emission Spectroscopy (OES)	p. 240
Infrared Spectroscopy	p. 243
Ellipsometry	p. 244
Ion Energy Probe	p. 245
Challenges of Deposition at High Growth Rates and Low Substrate Temperatures	p. 246
Growth-Process Models	p. 246
Inhomogeneity of Growth	p. 250
Growth at High Deposition Rates	p. 251
Silane Dissociation Efficiency and Depletion Criteria for nc-Si Deposition	p. 252
Low-Temperature (LT) Deposition	p. 254
Structural Evolution at Low Temperature	p. 257
Transient Plasma	p. 260
Upscaling to Large-Area and Industrial Processing: Critical Analysis of Various Fabrication Processes	p. 270
Acknowledgements	p. 273
References	p. 273
Modeling of Thin-Film Deposition Processes	p. 287
Introduction	p. 287
Modeling the Plasma Discharge	p. 290
Modeling of the Gas Phase and Surface Kinetics	p. 295
Gas-Phase Kinetic Scheme	p. 297
Surface Kinetic Scheme	p. 301
On the Consistent Solution of the Plasma Discharge and Kinetic Models: Theory and Examples	p. 303
Modeling of the Thin-Film Morphological Evolution	p. 303
Status of the Field and Perspectives	p. 308
References	p. 309
Thin-Film Silicon Solar Cells	p. 311
Introduction	p. 311
Second-Generation Solar Cells: Advantages Compared to the First Generation	p. 312
Drift-Type Thin-Film Silicon Solar Cells: Substrates and Configuration	p. 314
Material Considerations for Thin-Film Silicon Solar Cells	p. 316
Amorphous Silicon	p. 316
Amorphous Silicon-Germanium	p. 317
Nanocrystalline Silicon	p. 317
Light Confinement	p. 318
Present Status of Drift-Type Thin-Film Silicon Solar Cells	p. 321
Recent R&D Results on Thin-Film Silicon Solar Cells	p. 322
Industrial Scenario	p. 322
Technological Issues	p. 325
High Deposition Rate	p. 325
Thin Cells	p. 325
Third-Generation Thin-Film Silicon Cell	p. 329
Solar Cells on Plastics	p. 331
Transfer Method	p. 331
Direct Deposition	p. 332
Hybrid Cells	p. 334
Industrial Scenario of Thin-Film Silicon-based Solar Cells	p. 336
Challenges for Thin-Film Silicon Solar-Module Fabrication	p. 338
Acknowledgements	p. 341
References	p. 341
Innovative Quantum Effects in Silicon for Photovoltaic Applications	p. 355
Basic Principles of 3rd-Generation Solar Cells	p. 355
The Need for a New Generation of Solar Cells	p. 355
Limitations in Early Generations	p. 356
3rd-Generation Options	p. 357
The Advantages of Using Silicon Nanocrystals	p. 359
Fabrication and Advantages of Si-NCs	p. 359
Quantum Confinement Effect in Si-NCs	p. 360
Applications of Si-NCs in the 3rd-Generation Solar Cells	p. 362
All-Silicon Tandem Solar Cells	p. 362
Hot-Carrier Solar Cells	p. 364
Intermediate-Band Solar Cells	p. 366
Multiple-Carrier Generation	p. 369
Downshifter Cell	p. 372
Challenges and Solutions	p. 375
Size Control	p. 375
Carrier Transport	p. 375
Absorption	p. 378
Technological Constraints	p. 381
Conclusions	p. 381
Acknowledgements	p. 381
References	p. 381
Index	p. 393
Table of Contents provided by Ingram. All Rights Reserved.