Table of contents 4.6.2 Silicon crystal fabrication 4.6.3 Rapid thermal processing 4.7 Summary points 4.8 Homework 4.9 Suggested Readings and Reference 5. ENGINEERING ELECTRONIC STRUCTURE 195 5.1 Linking atomic orbitals to bands 5. 1. 1 Homopolar semiconductors 5.1.2 Heteropolar compounds 5.2 LCAO: from atomic orbitals to bands 5.3 Common semiconductor energy band 5.4 Pressure and temperature dependence 5.5 Applications 226 5.5. 1 Experimental band structures 5.5.2 Gunn diodes 5.6 Summary points 5.7 Homework 233 5.8 Suggested readings references 235 6 SEMICONDUCTOR ALLOYS 237 6. 1 Alloy selection 6.1.1 Overview 6. 1.2 Choosing alloy constituents 241 6.2 Semiconductor alloy thermodynamics 245 6.2. 1 Regular solution theory revisited 6.2.2 Ternary and quaternary solutions 249 6.2.3 More mechanisms for alloy orde 6.3 Band gap bowing 255 6.3. 1 Binary and pseudobinary alloys 6.3.2 Bowing in quaternary alloys 260 6.4 Silicon-germanium alloys 6.4.1 Structure and solubility 262 6.4.2 Band gap engineering 6.4.3 Alloying and carrier mobility 6.5 Metastable semiconductor alloys 6.6 Applications 6.6.1 Heterojunction bipolar transistors 72 6. 7 Summary points 6.8 Homework 6.9 Suggested rea references 285
195 5.1 Linking atomic orbitals to bands ...................................................................196 5.1.1 Homopolar semiconductors ................................................................197 5.1.2 Heteropolar compounds ......................................................................201 5.2 LCAO: from atomic orbitals to bands...........................................................206 5.3 Common semiconductor energy bands .........................................................215 5.4 Pressure and temperature dependence...........................................................223 5.5 Applications...................................................................................................226 5.5.1 Experimental band structures..............................................................226 5.5.2 Gunn diodes ........................................................................................228 5.6 Summary points.............................................................................................232 5.7 Homework .....................................................................................................233 5.8 Suggested readings & references...................................................................235 237 6.1 Alloy selection...............................................................................................238 6.1.1 Overview .............................................................................................238 6.1.2 Choosing alloy constituents ................................................................241 6.2 Semiconductor alloy thermodynamics..........................................................245 6.2.1 Regular solution theory revisited ........................................................245 6.2.2 Ternary and quaternary solutions........................................................249 6.2.3 More mechanisms for alloy ordering ..................................................252 6.3 Band gap bowing...........................................................................................255 6.3.1 Binary and pseudobinary alloys..........................................................255 6.3.2 Bowing in quaternary alloys ...............................................................260 6.4 Silicon-germanium alloys..............................................................................261 6.4.1 Structure and solubility .......................................................................262 6.4.2 Band gap engineering..........................................................................264 6.4.3 Alloying and carrier mobility..............................................................267 6.5 Metastable semiconductor alloys ..................................................................268 6.6 Applications...................................................................................................272 6.6.1 Heterojunction bipolar transistors.......................................................272 6.6.2 Solar cells ............................................................................................276 6.7 Summary points.............................................................................................280 6.8 Homework .....................................................................................................282 6.9 Suggested readings & references...................................................................285 Table of Contents xiii 4.7 Summary points.............................................................................................189 4.8 Homework .....................................................................................................191 4.9 Suggested Readings and References.............................................................194 4.6.2 Silicon crystal fabrication ...................................................................180 4.6.3 Rapid thermal processing....................................................................187 5. ENGINEERING ELECTRONIC STRUCTURE 6. SEMICONDUCTOR ALLOYS
Table of contents 7 DEFECTS IN SEMICONDUCTORS 289 7.1 Point defects 7. 1. 1 Electronic states due to point defects 291 7. 1.2 Shallow levels 7.1.3 Depth of intrinsic defects 7. 1. 4 Ionization of defects 7.1.5 Point defect densities 7.1.6 Vacancies and dopant diffusivity 7.2 Line defects 311 7.3 Strain relief in heterostructures 7.3.1 Energetics of strain relief 7.3.2 Misfit dislocations 328 7.3.3 Dislocation dynamIcs 7.3.4 Reducing problems due to strain relief 74 Planar and volume defects 7.4.1 Twins and stacking faults 337 7.4.2 Surfaces, interfaces, grain boundaries 340 7.4.3 Volume defects 343 7.5 SiC: a case study in stacking faults 7.6 Summary points 349 7.7 Homework 352 7.8 Suggested readings references 8. AMORPHOUS SEMICONDUCTORS 357 8. 1 Structure and bonding. 358 8.2 Hydrogenated amorphous Si 8.3 Deposition methods for a-Si 366 8.4E 8.4.1 Carrier transport and mobility 8.4.2 Mobility measurements 8.4.3 Doping 372 8.4.4 Short-range order 373 8.5 Optical properties 374 8.6 Amorphous semiconductor alloys 8.7 Applications 8.7.1 Thin film transistors 8.8 Summary points 8.9 Homework 8.10 Suggested readings and references 392
7.2 Line defects....................................................................................................311 7.3 Strain relief in heterostructures .....................................................................320 7.3.1 Energetics of strain relief ....................................................................322 7.3.2 Misfit dislocations...............................................................................328 7.3.3 Dislocation dynamics..........................................................................329 7.3.4 Reducing problems due to strain relief ...............................................336 7.4 Planar and volume defects.............................................................................337 7.4.1 Twins and stacking faults....................................................................337 7.4.2 Surfaces, interfaces, grain boundaries.................................................340 7.4.3 Volume defects....................................................................................343 7.5 SiC: a case study in stacking faults ...............................................................344 7.6 Summary points.............................................................................................349 7.7 Homework .....................................................................................................352 7.8 Suggested readings & references...................................................................355 357 8.1 Structure and bonding....................................................................................358 8.2 Hydrogenated amorphous Si .........................................................................364 8.3 Deposition methods for a-Si..........................................................................366 8.4 Electronic properties......................................................................................367 8.4.1 Carrier transport and mobility.............................................................367 8.4.2 Mobility measurements.......................................................................370 8.4.3 Doping.................................................................................................372 8.4.4 Short-range order ................................................................................373 8.5 Optical properties ..........................................................................................374 8.6 Amorphous semiconductor alloys .................................................................377 8.7 Applications...................................................................................................380 8.7.1 Thin film transistors ............................................................................380 8.7.2 Solar cells ............................................................................................383 8.8 Summary points.............................................................................................389 8.9 Homework .....................................................................................................391 8.10 Suggested readings and references..............................................................392 xiv Table of Contents 289 7.1 Point defects ..................................................................................................289 7.1.1 Electronic states due to point defects..................................................291 7.1.2 Shallow levels .....................................................................................295 7.1.3 Depth of intrinsic defects ....................................................................299 7.1.4 Ionization of defects............................................................................300 7.1.5 Point defect densities...........................................................................302 7.1.6 Vacancies and dopant diffusivity........................................................308 7. DEFECTS IN SEMICONDUCTORS 8. AMORPHOUS SEMICONDUCTORS
Table of contents 9. ORGANIC SEMICONDUCTORS 395 9.1 Materials overview 9.1.1 Conjugated organic materials... 9.1.2 ionized organic molecular structures 9.2 Overview of organic devices 9.2.1 Light 9.2.2 Transistors 9.3 Molecular optoelectronic materials 9.3.1 Molecular electron transporters 415 9.3.2 Molecular hole transporters 9.3.3 Dye molecules 9.3.4 Molecules for thin film transistors 427 9.4 Polymer optoelectronic organics 428 9.4.1 Polymers for organic light emitting devices 9.4.2 Polymers for transistors 434 9.5 Contact to organic materials 436 9.5.1 The cathode contact 436 9.5.2 The anode contact 9.6 Defects in organic materials 9.7 Patterning organic materials 442 9.8 Summary points 446 9.9 Homework 9.10 Suggested readings references 10. THIN FILM GROWTH PROCESSES 455 10. 1 Growth processes 455 0.2 Gas phase transport 0.3 Adsorption. 0.4 Desorpt 10.5 Sticking coefficient surface coverage 10.6 Nucleation growth of thin films 0.7 Surface diffusion 10.8 Surface energy 10.9 Morphology determined by nucleation 10.10 Microstructure evolution 484 10.11 Residual stress and adhesion 10.12 Applications 10.12. 1 Adsorption, desorption and binding of H to Si 488 10. 12.2 Surface processes in GaAs epitaxial growth 491 10.13 Summary points 10.14 Homework problems 10.15 Suggested readings references
9.4 Polymer optoelectronic organics ...................................................................428 9.4.1 Polymers for organic light emitting devices .......................................429 9.5 Contact to organic materials..........................................................................436 9.5.1 The cathode contact.............................................................................436 9.5.2 The anode contact ...............................................................................439 9.6 Defects in organic materials ..........................................................................440 9.8 Summary points.............................................................................................446 9.9 Homework .....................................................................................................448 9.10 Suggested readings & references.................................................................450 455 10.1 Growth processes.........................................................................................455 10.2 Gas phase transport......................................................................................460 10.3 Adsorption....................................................................................................461 10.4 Desorption....................................................................................................464 10.5 Sticking coefficient & surface coverage......................................................466 10.6 Nucleation & growth of thin films...............................................................468 10.7 Surface diffusion..........................................................................................474 10.8 Surface energy .............................................................................................477 10.9 Morphology determined by nucleation........................................................481 10.10 Microstructure evolution............................................................................484 10.11 Residual stress and adhesion......................................................................485 10.12 Applications ...............................................................................................488 10.12.1 Adsorption, desorption and binding of H to Si ............................488 10.12.2 Surface processes in GaAs epitaxial growth................................491 10.13 Summary points .........................................................................................496 10.14 Homework problems..................................................................................499 10.15 Suggested readings & references...............................................................502 Table of Contents xv 395 9.1 Materials overview ........................................................................................395 9.1.1 Conjugated organic materials..............................................................396 9.1.2 Ionized organic molecular structures ..................................................403 9.2 Overview of organic devices .........................................................................407 9.2.1 Light emitting devices.........................................................................408 9.2.2 Transistors ...........................................................................................411 9.3 Molecular optoelectronic materials ...............................................................414 9.3.1 Molecular electron transporters...........................................................415 9.3.2 Molecular hole transporters.................................................................417 9.3.3 Dye molecules.....................................................................................420 9.3.4 Molecules for thin film transistors ......................................................427 9.4.2 Polymers for transistors.......................................................................434 9. ORGANIC SEMICONDUCTORS 10. THIN FILM GROWTH PROCESSES 9.7 Patterning organic materials ..........................................................................442
XVI Table of contents 11. PHYSICAL VAPOR DEPOSITION 505 I1.1 Evaporation... 11. 1. 1 Basic system geometries 11.1.2 Sources 11.1.3 Vapor pressure 11.2 Monitoring deposition rates 11. 2. 1 Simple rate monitoring methods 518 11.2.2 Reflection high-energy electron diffraction 11.3 Sputtering 11.3. 1 Sputtering yield 527 11.3.2 Energetic particles 11.3.3 Sputtering systems 11.3. 4 Glow discharge basics. 542 11.4 Fast particle modification of films 11.5 Application l16 Summary points… 11.7 Homework problems 11. 8 Suggested readings references 12. CHEMICAL VAPOR DEPOSITION 573 12.1 Overview 12.2 CVD apparatus 578 12. 3 Gas flow in CVD reactors 2 4 Reactant selection and design .584 12.5 Stimulated CVD 587 12.6 Selective CVD 12.7 Atomic lay 12.8 Sample CVD and ALD processes 12.9 Summary points 12. 10 Homework problems 12. 1 1 Suggested readings references APPENDⅨX 611 Useful constants Units 612 Unit conversions 612 NDEX 615
11.5 Application ..................................................................................................560 11.6 Summary points...........................................................................................564 11.7 Homework problems ...................................................................................567 11.8 Suggested readings & references.................................................................570 573 12.1 Overview......................................................................................................574 12.2 CVD apparatus ............................................................................................578 12.3 Gas flow in CVD reactors ...........................................................................581 12.4 Reactant selection and design......................................................................584 12.5 Stimulated CVD ..........................................................................................587 12.6 Selective CVD .............................................................................................591 12.8 Sample CVD and ALD processes ...............................................................597 12.9 Summary points...........................................................................................604 Useful constants....................................................................................................611 Units......................................................................................................................612 Unit conversions ...................................................................................................612 xvi Table of Contents 12.10 Homework problems..................................................................................606 12.11 Suggested readings & references ...............................................................608 505 11.1 Evaporation..................................................................................................505 11.1.1 Basic system geometries ..................................................................506 11.1.2 Sources .............................................................................................508 11.1.3 Vapor pressure .................................................................................516 11.2 Monitoring deposition rates.........................................................................517 11.2.1 Simple rate monitoring methods......................................................518 11.2.2 Reflection high-energy electron diffraction.....................................520 11.3 Sputtering.....................................................................................................526 11.3.1 Sputtering yield ................................................................................527 11.3.2 Energetic particles............................................................................533 11.3.3 Sputtering systems ...........................................................................539 11.3.4 Glow discharge basics......................................................................542 11.4 Fast particle modification of films ..............................................................553 APPENDIX 611 INDEX 615 11. PHYSICAL VAPOR DEPOSITION 12. CHEMICAL VAPOR DEPOSITION 12.7 Atomic layer deposition...............................................................................594
LIST OF TABLES Selected Significant Events in the Development of Semiconductor Microelectronics 1900-2000 Typical Piezoelectric Stress Coefficients of Selected Materials Thermal Cnductivities of selected materials ion Ratios of Impurities in Sil Atomic and Molecular Orbital Energies Bond Orbital Energies Pressure and Temperature Dependences of Selected Semiconductor Minimum Pa Ideal Properties for Traps and Recombination Centers
LIST OF TABLES Typical Piezoelectric Stress Coefficients of Selected Materials ................................52 Selected Significant Events in the Development of Semiconductor Microelectronics, 1900-2000 ........................................................................................3 Thermal Cnductivities of Selected Materials .............................................................55 Segregation Ratios of Impurities in Silicon..............................................................185 Atomic and Molecular Orbital Energies...................................................................206 Bond Orbital Energies ..............................................................................................206 Pressure and Temperature Dependences of Selected Semiconductor Minimum Energy Gaps..............................................................................................................224 Semiconductor Alloy Bowing Parameters................................................................259 Ideal Properties for Traps and Recombination Centers............................................293 Fits to Vapor Pressures of Selected Elements Based on Equation 11.2 ...................516