Conductive Atomic Force Microscopy Applications in Nanomaterials

Oxide Films and Conduction AFM xi

List of Contributors xv

1 History and Status of the CAFM 1
Chengbin Pan, Yuanyuan Shi, Fei Hui, Enric Grustan-Gutierrez, and Mario Lanza

1.1 The Atomic Force Microscope 1

1.2 The Conductive Atomic Force Microscope 4

1.3 History and Status of the CAFM 9

1.4 Editor’s Choice: On the Use of CAFM to Study Nanogenerators Based on Nanowires 16

1.5 Conclusions 20

References 20

2 Fabrication and Reliability of Conductive AFM Probes 29
Oliver Krause

2.1 Introduction 29

2.2 Manufacturing of Conductive AFM Probes 30

2.2.1 Thin Film Cantilever 30

2.2.2 Corner Tips 30

2.2.3 Etched Silicon Probes 31

2.2.4 Coating of Probes 32

2.2.5 ConductiveThin Film Probes 34

2.2.6 Material Conversion 35

2.3 How to Choose Your C-AFM Tip 36

2.3.1 Cantilever Choice 36

2.3.2 Tip Material Choice 36

2.3.3 Resolution of C-AFM Tips 37

2.4 TipWear and Sample Damage: Applicable Forces and Currents in C-AFM 38

2.4.1 TipWear: MechanicalWear – Varying Forces 38

2.4.2 TipWear: MechanicalWear – Different Materials 39

2.4.3 TipWear: ElectricalWear 39

2.4.4 Tip Damage by Excess Voltage/High Currents 40

2.4.5 Damaging the Sample Surface 42

2.5 Conclusions 43

References 43

3 Fundamentals of CAFM Operation Modes 45
Guenther Benstetter, Alexander Hofer, Donping Liu,Werner Frammelsberger, and Mario Lanza

3.1 Introduction 45

3.2 Tip-Sample Interaction: Contact Area, Effective Emission Area, and Conduction Mechanisms 47

3.2.1 CAFM Tip on Metallic Surfaces 49

3.2.2 CAFM Tip on Semiconducting Surfaces 50

3.2.3 CAFM Tip on Insulating Surfaces 52

3.3 Work Function Difference and Offset Voltage 56

3.4 Operation Modes 60

3.4.1 Contact Mode 61

3.4.2 PeakForce Mode 62

3.4.3 Torsional Resonance Mode 63

3.5 Case Studies 64

3.5.1 Defects in SiC after Plasma Exposure in Fusion Reactors 64

3.5.2 Electrical Conductivity of Dislocations in GaN 67

3.5.3 Microstructure and Local Electrical Conductivity of Laser-Sintered Nanoparticles 69

3.6 Conclusion and Future Perspectives 70

Acknowledgment 70

References 71

4 Investigation of High-k Dielectric Stacks by C-AFM: Advantages, Limitations, and Possible Applications 79
Mathias Rommel and Albena Paskaleva

4.1 Introduction 79

4.2 Comparison BetweenMacroscopic I–V Measurements and C-AFM 81

4.3 Influence of Displacement Currents on the Sensitivity of C-AFM Measurements 85

4.4 Applications of C-AFM 89

4.4.1 Morphology ofThin Dielectric Films 89

4.4.2 Assessment of the Interfacial SiO2 Thickness 94

4.4.3 Trapping Phenomena and DegradationMechanism in High-k Dielectric Stacks 98

4.4.4 Reliability of High-k Dielectric Films 104

4.4.4.1 Gate Oxide Reliability at the Nanoscale 104

4.4.4.2 In-Depth Analysis of Bimodal TDDB Distributions 109

4.5 Conclusion 112

References 113

5 Characterization of Grain Boundaries in Polycrystalline HfO2 Dielectrics 119
Shubhakar Kalya, Sean Joseph O’Shea, and Kin Leong Pey

5.1 Introduction 119

5.2 Experimental Details and Sample Specifications 120

5.3 Formation of Grain Boundaries and Its Local Electrical Properties in HfO2 Dielectric 120

5.4 RVS and CVS Stressing of HfO2/SiOx Dielectric Stack 124

5.5 Uniform Stressing with Successive Scanning in CAFM Mode 126

5.6 Conclusions 130

References 130

6 CAFM Studies on Individual GeSi Quantum Dots and Quantum Rings 133
RongWu, Shengli Zhang, Yi Lv, Fei Xue, Yifei Zhang, and Xinju Yang

6.1 Introduction 133

6.2 Conductive Properties of Individual GeSi QDs and QRs 134

6.2.1 Conductive Property Studies on Individual GeSi QDs 135

6.2.1.1 Growth Temperature Dependence 135

6.2.1.2 Electrical Property Changing with the Capping of Si Layer 137

6.2.2 The Conductive Mechanism of GeSi QRs 140

6.3 Modulating the Conductive Properties of GeSi QDs 144

6.3.1 Oxidation and Normal Force 144

6.3.2 Bias Voltage 146

6.3.3 Inter-Dot Coupling 149

6.4 SimultaneousMeasurements of Composition and Current

Distributions of GeSi QRs 152

6.5 Conclusions 157

References 157

7 Conductive Atomic ForceMicroscopy of Two-Dimensional Electron Systems: FromAlGaN/GaN Heterostructures to Graphene and MoS2 163
Filippo Giannazzo, Gabriele Fisichella, Giuseppe Greco, Patrick Fiorenza, and Fabrizio Roccaforte

7.1 Introduction 163

7.2 Nanoscale Electrical Characterization of AlGaN/GaN Heterostructures 164

7.2.1 Contacts to AlGaN/GaN Heterostructures 165

7.2.2 Electrical Nanocharacterization of AlGaN Surface Passivated by a RapidThermal Oxidation 168

7.2.3 CAFMon Dielectrics for Gate Insulated AlGaN/GaN Transistors 169

7.3 CAFM Characterization of Graphene and MoS2 171

7.3.1 Local Electrical Properties of Graphene 2DEG 173

7.3.2 Nanoscale Inhomogeneity of the Schottky Barrier and Resistivity in MoS2 175

7.3.3 Graphene Contacts to AlGaN/GaN Heterostructures 178

7.4 Conclusions 181

Acknowledgments 182

References 182

8 Nanoscale Three-Dimensional Characterization with Scalpel SPM 187
Umberto Celano andWilfried Vandervorst

8.1 Introduction 187

8.2 SPM Metrology with Depth Information 188

8.3 Scalpel SPM: A Tip-Based Slice-and-ViewMethodology 190

8.3.1 General Description 190

8.3.2 Practical Implementation 193

8.4 Applications 196

8.4.1 Scalpel SPM for 3D Observation of Conductive Filaments in Resistive Memories 196

8.4.2 Mechanisms for Filament Growth 200

8.4.3 Chemical Nature of the Filament 202

8.4.4 Scalpel SPM for Failure Analysis 203

8.5 Conclusions and Outlook 206

References 207

9 Conductive Atomic Force Microscopy for Nanolithography Based on Local Anodic Oxidation 211
Matteo Lorenzoni and Francesc Pérez-Murano

9.1 Introduction to AFM Nanolithography 211

9.2 Local Anodic Oxidation 212

9.3 Kinetics of LAO 214

9.4 Measurement of Electrical Current During LAO 217

9.5 Conclusions 219

Acknowledgments 219

References 220

10 Combination of Semiconductor Parameter Analyzer and Conductive Atomic ForceMicroscope for Advanced Nanoelectronic Characterization 225
Vanessa Iglesias, Xu Jing, and Mario Lanza

10.1 Introduction 225

10.2 Combination of SPA and CAFM for Local Channel Hot Carrier Degradation Analysis 227

10.3 Combination of CAFMand SPA for Resistive Switching Analyses 230

10.3.1 Device-Level Stress with SPA Followed by CAFM Characterization 230

10.3.2 Direct Connection of SPA to the CAFM 235

10.4 Conclusions 237

References 238

11 Design and Fabrication of a Logarithmic Amplifier for Scanning Probe Microscopes to AllowWide-Range Current Measurements 243
Lidia Aguilera and Joan Grifoll-Soriano

11.1 Introduction 243

11.2 Fabrication of a Logarithmic Preamplifier for CAFMS 244

11.2.1 Design 244

11.2.2 Fabrication and Testing 249

11.2.2.1 Printed Circuit Board 249

11.2.2.2 Cleaning 250

11.2.2.3 Decoupling 250

11.2.2.4 Input and Output Isolation 251

11.2.2.5 Unexpected Passive Components in the PCB 251

11.2.3 Implementation in a CAFM and Case Study 255

11.3 Conclusions 260

References 261

12 Enhanced Current Dynamic Range Using ResiScopeTM and Soft-ResiScope AFMModes 263
Louis Pacheco and Nicolas F. Martinez

12.1 Introduction 263

12.2 Conductive AFM 264

12.3 ResiScopeTM Mode 267

12.4 Soft-ResiScope Mode 271

12.5 Conclusions 275

References 275

13 Multiprobe Electrical Measurements without Optical Interference 277
David Lewis, Andrey Ignatov, Sasha Krol, Rimma Dekhter, and Alina Strinkovsky

13.1 Introduction 277

13.2 The Multiprobe Platform: Design and Key Features 279

13.2.1 The Scanner 279

13.2.2 The Probes 281

13.2.3 Feedback of Multiprobe Systems 282

13.3 The Present and the Future 284

13.3.1 AFM Multiprobe Application 284

13.3.2 Optical Multiprobe Operation 285

13.3.3 Thermal Measurements 285

13.3.4 NanoElectrical Transport Measurements 287

13.3.5 New Horizons in Multiprobe Measurements 291

13.4 Conclusions 292

References 293

14 KPFM and its Use to Characterize the CPD in Different Materials 297
Yijun Xia and Bo Song

14.1 Introduction 297

14.2 Kelvin Probe Force Microscopy 297

14.2.1 Basic Principle of Kelvin Probe Force Microscopy 297

14.2.2 KPFM OperationalModes: AM- and FM-Mode 299

14.2.3 KPFM Measurement, at Ambient or UHV Conditions 300

14.3 Applications of KPFM 301

14.3.1 KPFM on Conventional Inorganic Materials 301

14.3.1.1 Metallic Nanostructures 301

14.3.1.2 Semiconductor Surfaces 302

14.3.2 KPFM on Organic Adsorbates on Surfaces 304

14.3.3 Characterization of the Electrical Properties of Nanoscaled Devices 305

14.3.3.1 Junctions and Heterostructrues 305

14.3.3.2 Transistors 307

14.3.3.3 Solar Cells 308

14.4 Conclusion and Outlook 311

Acknowledgment 312

References 312

15 Hot Electron Nanoscopy and Spectroscopy (HENs) 319
Andrea Giugni, Bruno Torre, Marco Allione, Gerardo Perozziello, Patrizio Candeloro, and Enzo Di Fabrizio

15.1 Introduction 319

15.2 Coupling Schemes 321

15.3 Plasmonic Device and Optical Characterization 326

15.4 Theoretical Section 327

15.4.1 Semiclassical Considerations 329

15.4.2 Quantum Mechanical Considerations 333

15.4.3 Quantum Confinement 334

15.5 HENs Measurements: Plasmon-Assisted Current Maps and Ultimate Spatial Resolution 335

15.5.1 Hot Electron Mapping 336

15.5.2 Hot Electron Resolution Limit 338

15.6 Kelvin Probe, HENs, and Electrical Techniques 340

15.6.1 SKPMTheoretical Frame: a Short Introduction 340

15.6.2 HENs 344

15.6.2.1 Spatial Resolution 344

15.6.2.2 Sensitivity and Specificity 344

15.7 Fast Pulses in Adiabatic Compression for Hot Electron Generation 347

15.8 Conclusion 348

Acknowledgments 349

References 349

Index 355