Cover image for Internal photoemission spectroscopy : principles and applications
Title:
Internal photoemission spectroscopy : principles and applications
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Publication Information:
Amsterdam : Elsevier Science, 2008
ISBN:
9780080451459

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30000010163026 QD96.A8 A32 2008 Open Access Book Book
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Summary

Summary

The monographic book addresses the basics of the charge carrier photoemission from one solid to another - the internal photoemission, (IPE) - and different spectroscopic applications of this phenomenon to solid state heterojunctions. This is the first book in the field of IPE, which complements the conventional external photoemission spectroscopy by analysing interfaces separated from the sample surface by a layer of a different solid or liquid. IPE is providing the most straightforward and, therefore, reliable information regarding the energy spectrum of electron states at interfaces. At the same time, the method provides the unique capability of analysing the heterostructures relevant to the modern micro- and nano-electronic devices as well as new materials involved in their design and fabrication.In addition to the discussion of fundamental physical and technical aspects of IPE spectroscopic applications, several "hot" topics are addressed. These include development of new insulating materials for advances Si MOS technology (both high-k gate insulators and low-k dielectrics for interconnect insulation), metal gate materials, development of heterostructures based on high-mobility semiconductors, etc. Thanks to a considerable activity in this field over the last few years, the recent results concerning band structure of most important interfaces involving novel materials can now be documented.


Author Notes

Professor V. Afanas'ev devoted more than 25 years of research to development of novel experimental methods for interface characterization. In particular, a number of techniques based on internal photoemission phenomena were shown to provide unique information regarding electron states in thin films of solids and at their interfaces. In recent years these methods were successfully applied to characterize novel semiconductor heterostructures for advanced micro- and nano-electronic devices.


Table of Contents

Prefacep. xi
List of Abbreviationsp. xiii
List of Symbolsp. xv
1 Preliminary Remarks and Historical Overviewp. 1
1.1 General Concept of IPEp. 1
1.2 IPE and Materials Analysis Issuesp. 2
1.3 Interfaces of Wide Bandgap Insulatorsp. 5
1.4 Metal-Semiconductor Barriersp. 8
1.5 Energy Barriers at Semiconductor Heterojunctionsp. 12
1.6 Energy Barriers at Interfaces of Organic Solids and Molecular Layersp. 14
1.7 Energy Barriers at Interfaces of Solids with Electrolytesp. 18
2 Internal versus External Photoemissionp. 23
2.1 Common Steps in Internal and External Photoemissionp. 23
2.1.1 Optical excitationp. 24
2.1.2 Transport of excited electron to the surface of emitterp. 25
2.1.3 Escape from emitter: the Fowler modelp. 29
2.2 IPE-Specific Featuresp. 32
2.2.1 Effects of the collector DOSp. 32
2.2.2 Effects associated with occupied electron states in the collectorp. 34
2.2.3 Interface barrier shapep. 35
2.2.4 Electron scattering in the image-force potential wellp. 39
2.2.5 Effects of fixed charge in the collectorp. 42
2.2.6 Collector transport effectsp. 45
3 Model Description and Experimental Realization of IPEp. 48
3.1 The Quantum Yieldp. 48
3.2 Quantum Yield as a Function of Photon Energyp. 50
3.3 Quantum Yield as a Function of Electric Fieldp. 53
3.4 Conditions of IPE Observationp. 57
3.4.1 Injection-limited versus transport-limited currentp. 57
3.4.2 Thermoionic emission versus photoemissionp. 59
3.4.3 Photocurrents related to light-induced redistribution of electric fieldp. 60
3.5 Experimental Approaches to IPEp. 62
3.5.1 IPE sample designp. 62
3.5.2 Optical input designsp. 64
3.5.3 IPE signal detectionp. 65
4 Internal Photoemission Spectroscopy Methodsp. 67
4.1 IPE Threshold Spectroscopyp. 68
4.1.1 Contributions of different bands to IPEp. 68
4.1.2 The Schottky plot analysisp. 72
4.1.3 Separation of different contributions to photocurrentp. 73
4.2 IPE Yield Spectroscopyp. 75
4.2.1 Mechanism of the yield modulationp. 76
4.2.2 Application of the IPE yield modulation to Si surface monitoringp. 78
4.2.3 Model for the optically induced yield modulationp. 82
4.3 Spectroscopy of Carrier Scatteringp. 85
4.3.1 Scattering in emitterp. 85
4.3.2 Scattering in collectorp. 88
4.4 PC and PI Spectroscopyp. 92
4.4.1 Intrinsic PC of collectorp. 92
4.4.2 Spectroscopy of PIp. 97
4.4.3 PI of near-interface states in collector: the pseudo-IPE transitionsp. 101
5 Injection Spectroscopy of Thin Layers of Solids: Internal Photoemission as Compared to Other Injection Methodsp. 107
5.1 Basic Approaches in the Injection Spectroscopyp. 108
5.2 Charge Injection Using IPEp. 109
5.3 Carrier Injection by Tunnellingp. 112
5.4 Excitation of Carriers in Emitter Using Electric Fieldp. 114
5.5 Electron-Hole Plasma Generation in Collectorp. 117
5.6 What Charge Injection Technique to Choose?p. 121
6 Trapped Charge Monitoring and Characterizationp. 124
6.1 Injection Current Monitoringp. 124
6.2 Semiconductor Field-Effect Techniquesp. 127
6.3 Charge Probing by Electron IPEp. 133
6.4 Charge Probing Using Trap Depopulationp. 137
6.5 Charge Probing Using Neutralization (Annihilation)p. 141
6.6 Monitoring the Injection-Induced Liberation of Hydrogenp. 145
7 Charge Trapping Kinetics in the Injection-Limited Current Regimep. 148
7.1 Necessity of the Injection-Limited Current Regimep. 148
7.2 First-Order Trapping Kinetics: Single Trap Modelp. 150
7.3 First-Order Trapping Kinetics: Multiple Trap Modelp. 152
7.4 Effects of Detrappingp. 154
7.5 Carrier Recombination Effectsp. 158
7.6 Trap Generation During Injectionp. 160
7.7 Trapping Analysis in Practicep. 161
8 Transport Effects in Charge Trappingp. 164
8.1 Strong Carrier Trapping Regimep. 164
8.2 Carrier Trapping Near the Injecting Interfacep. 169
8.3 Inhibition of Trapping by Coulomb Repulsionp. 172
8.4 Carrier Redistribution by Coulomb Repulsionp. 177
8.5 Injection Blockage and Transition to Space-Charge-Limited Currentp. 180
9 Semiconductor-Insulator Interface Barriersp. 182
9.1 Electron States at the Si/SiO[subscript 2] Interfacep. 183
9.1.1 Si/SiO[subscript 2] band alignmentp. 183
9.1.2 Si/SiO[subscript 2] interface dipolesp. 184
9.1.3 Si/SiO[subscript 2] barrier modification by trapped chargesp. 186
9.1.4 Trapped ions at Si/SiO[subscript 2] interfacep. 188
9.2 High-Permittivity Insulators and Associated Issuesp. 189
9.2.1 Application of high-permittivity insulatorsp. 189
9.2.2 Bandgap width in deposited oxide layersp. 192
9.3 Band Alignment at Interfaces of Silicon with High-Permittivity Insulatorsp. 195
9.3.1 Band alignment at interfaces of Si with elemental metal oxidesp. 195
9.3.2 Interfaces of Si with complex metal oxidesp. 198
9.3.3 Interfaces of Si with non-oxide insulatorsp. 203
9.4 Band Alignment between Other Semiconductors and Insulating Filmsp. 208
9.4.1 Ge/high-permittivity oxide interfacesp. 209
9.4.2 GaAs/insulator interfacesp. 212
9.4.3 SiC/insulator interfacesp. 217
9.5 Contributions to the Semiconductor-Insulator Interface Barriersp. 221
10 Electron Energy Barriers between Conducting and Insulating Materialsp. 224
10.1 Interface Barriers between Elemental Metals and Oxide Insulatorsp. 225
10.1.1 Metal-SiO[subscript 2] interfacesp. 225
10.1.2 Interfaces of elemental metals with high-permittivity oxidesp. 227
10.2 Polycrystalline Si/Oxide Interfacesp. 231
10.3 Complex Metal Electrodes on Insulatorsp. 237
10.4 Modification of the Conductor/Insulator Barriersp. 242
11 Spectroscopy of Charge Traps in Thin Insulating SiO[subscript 2] Layersp. 245
11.1 Trap Classification through Capture Cross-Sectionp. 246
11.2 Electron Traps in SiO[subscript 2]p. 248
11.2.1 Attractive Coulomb trapsp. 248
11.2.2 Neutral electron traps in SiO[subscript 2]p. 249
11.2.3 Repulsive electron traps in SiO[subscript 2]p. 251
11.3 Hole Traps in SiO[subscript 2]p. 251
11.3.1 Attractive Coulomb hole trapsp. 252
11.3.2 Neutral hole traps in SiO[subscript 2]p. 252
11.4 Proton Trapping in SiO[subscript 2]p. 256
12 Conclusionsp. 260
Referencesp. 263
Indexp. 291