The handbook of electroluminescent materials

642 Pages·12.839 MB·English

by  D R Vij, Institute of Physics (Great Britain)

Series on Optics and Optoelectronics
Handbook of
Electroluminescent
Materials
Edited by
D R Vij
Department of Physics, Kurukshetra University,
Kurukshetra, India
Institute of Physics Publishing
Bristol and Philadelphia
Copyright 2004 IOP Publishing Ltd
# IOP Publishing Ltd 2004
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A cataloguerecord for this bookis available from the British Library.
ISBN0 7503 0923 7
Library ofCongress Cataloging-in-PublicationDataare available
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Copyright 2004 IOP Publishing Ltd
Contents
Prefacexiii
Acknowledgmentsxv
1Electroluminescence:anintroduction1
DHaranath,VirendraShankerandDRVij
1.1 Introduction 1
1.2 Fundamental physicalprocesses 4
1.2.1 Atomictransitions 4
1.3 High-field EL 5
1.3.1 Powderphosphor EL 5
1.3.2 Alternating current powder EL 6
1.3.3 Directcurrent powder EL 11
1.4 Injection EL 14
1.4.1 EL mechanism 14
1.5 Thin-film EL 15
1.5.1 Directcurrent thin-film EL 16
1.5.2 Alternating current thin-film EL 16
1.6 Recent developments inTFEL displays 21
References 21

PART 1 II–IV GROUPMATERIALS 25
2 Zinc sulphide 27
NigelShepherdandPaulHHolloway
2.1 Introduction and historical perspective 27
2.2 Phosphor fundamentals 31
2.2.1 Fundamentals ofatomictransitions 31
2.2.2 Luminescentcentres 35
2.2.3 Zinc sulphide—the host 41
2.2.4 Luminescentcentre–hostlattice interactions 48
v
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vi Contents
2.3 Zinc sulphide electroluminescent devices 56
2.3.1 Directcurrent thin-film devices 57
2.3.2 Alternating current thin-film devices 61
2.3.3 Directcurrent powder electroluminescence from
ZnS 107
2.3.4 Alternating current powderelectroluminescence
from ZnS 110
2.4 Summary 112
2.4.1 Practical approaches forenhancing luminancein
ZnS phosphors 112
2.4.2 ZnS devices in the FPD marketplace and current
trends 115
2.4.3 New applications forZnS devices and materials 116
Acknowledgment 117
References 117
3 Zincselenide andzinc telluride 124
MGodlewski,EGuziewiczandVYuIvanov
3.1 Introduction 124
3.2 Semiconductor-basedmonochromaticLEDs 125
3.2.1 Lightemitting diodes 125
3.3 White light sources 127
3.3.1 Principles ofwhitelight sources 127
3.3.2 Basics ofcolourmixing 128
3.4 Semiconductor-basedwhitelight sources 132
3.4.1 III–V based whiteLEDs 132
3.4.2 ZnSe and/or ZnTe? 132
3.5 Niche applications 134
3.5.1 White emission from thin films of ZnSe 134
3.5.2 Blueanti-Stokes emission from TM-doped ZnSe 141
3.5.3 Infrared intra-shell emissionin ZnSe:Cr 152
3.6 Summary 155
References 155
4 Cadmium chalcogenide nanocrystals 158
StephenMKelly,MaryO’NeillandTomStirner
4.1 Introduction 158
4.2 Theory 159
4.3 Empirical pseudopotentialmethod 160
4.3.1 Theory 160
4.3.2 CdTe nanospheres 161
4.3.3 CdTe nanorods 165
4.4 Effective-mass approximation 167
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Contents vii
4.4.1 Theory 167
4.4.2 Post-growth tuning of energy levels 169
4.4.3 Polarized emission 172
4.5 Synthesis 173
4.5.1 Hybridinorganic/organicLEDS 179
4.6 Conclusions 186
References 186
5 Alkalineearth sulphides 193
VirendraShankerandHarishChander
5.1 Introduction 193
5.2 Physical properties of ELemitting AES compounds 194
5.3 Thin film electroluminescence(TFEL) ofalkaline earth
sulphides 198
5.4 Fullcolour ELphophors 209
5.5 Phosphorsof commercial TFEL displaydevices 213
5.6 Phosphorsfor monochrome displays 214
5.7 Phosphorsfor colour displays 214
5.7.1 Blue-light emitting phosphors 214
5.7.2 Green-light emitting phosphors 214
5.7.3 Red-light emitting phosphors 215
5.7.4 White-emitting phosphors 215
References 216
6 Zinc oxide 217
ShashiBhushan
6.1 Introduction 217
6.2 Preparationmethods 217
6.2.1 Powders 217
6.2.2 Pellets 218
6.2.3 Thin films 218
6.2.4 Crystals 219
6.2.5 Nanocrystallites 220
6.3 Luminescence properties 221
6.3.1 General 221
6.3.2 Electrodes 232
6.3.3 Varistors 233
6.3.4 Ceramics 233
6.3.5 Hydrogenation 233
6.3.6 Excitonic 233
6.3.7 Mixedbasesand other forms 235
6.3.8 Nanocrystallites 237
6.4 Applications and future scope 238
References239
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viii Contents
PART 2 III–V GROUPMATERIALS 243
7 Galliumarsenideanditsternaryalloys(self-assembledquantumdots) 245
DWassermanandSALyon
7.1 Introduction 245
7.2 Quantum dot growth 247
7.3 Carriers inquantum dots 254
7.3.1 Electronic structure 255
7.3.2 Opticaltransitions 261
7.3.3 Electron lifetimes 262
7.4 Electroluminescence from quantum dots 264
7.4.1 Near-infrared luminescence 264
7.4.2 Quantum dot lasers 264
7.4.3 Mid-infrared electroluminescence 272
7.4.4 Single dot luminescence and single photon
emitters using QDs 275
7.5 Conclusion 277
References 277
8 Gallium phosphide and its wide-band gapternary and
quaternary alloys 282
AlexanderNPikhtinandOlgaLLazarenkova
8.1 Introduction 282
8.2. Gallium phosphide 283
8.2.1. Lattice,physical–chemical properties and
technological data 283
8.2.2. Electronic properties, electricalconductivity,
impurities and defects 286
8.2.3 Opticalproperties 291
8.2.4 Luminescence 300
8.2.5 Device technology and applications 314
8.3 Ternaryalloys 317
8.4 Quaternary alloys 329
8.5 Conclusion 341
Acknowledgments 341
References 341
9 Gallium nitride and relatedmaterials 348
MGodlewskiandAKozanecki
9.1 Introduction 348
9.2 Properties ofbuffer layers forGaN epitaxy 348
9.2.1 LT GaN buffer layer 349
9.3 Freestanding GaN layers forGaN epitaxy 354
9.3.1 Freestanding GaN layers—an alternative approach 355
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Contents ix
9.4 GaN-based laser diodes 357
9.4.1 Homo-epitaxiallaser diodes 358
9.4.2 Electron beampumping 360
9.5 GaN doped withrare earth ions 376
9.5.1 Introduction 376
9.5.2 Lattice location studiesof RE atoms in GaN 377
9.5.3 Emission of Er3þ ions inGaN 379
9.5.4 PL excitation spectroscopy of Er3þ inGaN 380
9.5.5 Analysis of Er site symmetry inGaN 383
References 387
PART 3 IV GROUP MATERIALS 391
10 Silicon and porous silicon 393
BernardGellozandNobuyoshiKoshida
10.1 Introduction 393
10.2 Background 395
10.2.1 Porous Si formation 395
10.2.2 Porous Si main characteristics 396
10.2.3 Porous Si photoluminescence 397
10.2.4 Definitions and requirements 398
10.3 EL from bulk Si and erbium 399
10.3.1 Bulk crystallineSi pn junction LEDs 399
10.3.2 Other ELdevices based on bulk crystallineSi 403
10.3.3 Er-doped bulk Si and SiO matrices 404
x
10.3.4 Er-doped Si nanoclusters 406
10.3.5 Other Er-doped Si-based devices 407
10.4 EL from low-dimensional Sistructures 408
10.4.1 Arrays ofSi nanocrystals and nanowires 409
10.4.2 Si-rich SiO simplesystems 411
2
10.4.3 Superlattices 414
10.5 Visible electroluminescence from PS 416
10.5.1 Overview 417
10.5.2 Porous Si incontact with aliquid 423
10.5.3 Differencesbetween wet and solid-stateEL 425
10.5.4 Devices includingan as-formed PSlayer 429
10.5.5 Porous Si formed from pn junctions 431
10.5.6 Partially-oxidized porousSi 433
10.5.7 Porous Si impregnated with other materials 437
10.5.8 Influence of thetop contact 441
10.5.9 Porous Si microcavities 444
10.5.10 Porous Si stabilization (surface chemistry and
capping ofporousSi) 447
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10.5.11 EL modulationspeed 448
10.5.12 Integration issue 449
10.6 Ballistic ELusing porous Si 451
10.6.1 Electron emissionfrom porous Siand its
mechanism 451
10.6.2 Further developments of electron emission from
porousSi 454
10.6.3 Electron emissionand flatpanel displaybasedon
porouspoly-Si 457
10.6.4 Solid-state planar luminescentdevices 458
10.7 Relatedoptical componentsbased on porousSi 460
10.7.1 Passive opticalcomponents: filters and
waveguides 460
10.7.2 Activeopticalcomponents:photodetectors,
memories, switching 462
10.8 Conclusion 465
References 466
11 Silicon/germanium superlattices 476
HartmutPresting
11.1 Introduction 476
11.2 Theory 477
11.2.1 Bandstructureand Brillouin zone foldingof
Si Ge superlattices 477
m n
11.2.2 Strain adjustment by a Si Ge buffer layer 482
1(cid:1)yb yb
11.2.3 EffectiveGe content and thevirtualsubstrate 483
11.3 Growthandcharacterization of Si Ge superlattices 485
m n
11.3.1 MBE growthof buffer and Si Ge SLS layers 485
m n
11.3.2 Characterization ofSi Ge SLS by XRD,
m n
TEM and Raman spectroscopy 488
11.4 Electroluminescence and related properties 497
11.4.1 Opticaland electrical characterization of10ML
Si Ge SLS 502
m n
11.4.2 Capacitance–voltage 503
11.4.3 Short-circuitcurrent and electroluminescence 504
11.5 Outlook 508
Acknowledgments 508
References 508
12 Diamond films 511
DeanMAslam
12.1 Introduction 511
12.1.1 Luminescence inindirectgap semiconductors 513
12.1.2 Hybrid bondingstructure of carbon 514
Copyright 2004 IOP Publishing Ltd
Contents xi
12.2 Diamondfilm growth technologies 515
12.2.1 Diamondfilm microfabrication technologies 516
12.2.2 Diamondsensor and microsystems technologies 517
12.3 Electroluminescence in carbon-based materials 519
12.3.1 Fieldemissionelectroluminescence 522
12.4 Future trends 528
Acknowledgments 528
References 528
PART 4 OTHERMATERIALS 531
13 Polymeric semiconductors 533
JieLiu,YijianShi,Tzung-FangGuoandYangYang
13.1 Introduction 533
13.2 Polymer morphology 535
13.2.1 Effects ofconcentration/spin-speed 535
13.2.2 Effects ofsolvent 539
13.2.3 Effects ofthermalannealing 544
13.3 The morphological dependenceof device performance 547
13.3.1 The film conductivity 547
13.3.2 Metal–polymer interfaces 548
13.3.3 Turn-on voltages 553
13.3.4 The emission spectrum 559
13.3.5 The quantum efficiency 566
13.4 Reduction of theinter-chain species using solid solutions 571
13.4.1 Inert spacer—polystyreneasthe host 571
13.4.2 Energy/charge transfer poly(9,9-dioctyfluorene)
asthe host 574
References 580
14 Liquid crystalline materials 583
StephenMKellyandMaryO’Neill
14.1 Introduction 583
14.2 Material properties forOLEDs 584
14.3 LCs forpolarized luminescence 587
14.4 Charge transporting LCs forOLEDs 592
14.5 Electroluminescent semiconductor LCs 594
14.6 LC polymers 594
14.7 LC oligomers 597
14.8 Small molecule LCs 598
14.9 LC polymer networks 604
14.10 Conclusions 608
References 609
Copyright 2004 IOP Publishing Ltd
xii Contents
15 High T oxide superconductors 614
c
DDShivagan,BMTodkarandSHPawar
15.1 Introduction 614
15.2 Luminescencein high-T oxide superconductors 615
c
15.2.1 Oxygen-dominated lattices 615
15.2.2 Defects 616
15.2.3 Opticaltransitions 617
15.2.4 Photoluminescence 618
15.2.5 Thermoluminescence 622
15.2.6 Cathodoluminescence 624
15.2.7 Electroluminescence 624
15.3 Y Ba Cu O superconductors 625
1 2 3 7(cid:1)(cid:1)
15.3.1 Role ofoxygencontent 626
15.3.2 Effect of Gd concentration 627
15.3.3 Effect of Mn substitution 629
Acknowledgments 631
References 632
Index 635

Copyright 2004 IOP Publishing Ltd