Van der Pauw method

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Table of contents

Acknowledgments
Abstract
1 2D materials and doping
1.1 Introduction
1.2 Electrostatic doping
1.3 Graphene
1.3.1 Electronic structure
1.3.2 Synthesis
1.3.3 Graphene characterization
1.3.4 Electronic transport properties
Scattering mechanisms and mobility
Mobility
Magnetotransport
1.3.5 Doping of graphene
Electrostatic doping
Chemical and substitutional doping
1.3.6 Graphene as transparent conducting electrode
1.4 Zinc oxide
1.4.1 Crystal and electronic structure
1.4.2 Crystal growth
RF magnetron sputtering
Other deposition techniques
1.4.3 Characterization of ZnO
X-ray diraction spectrum of ZnO
AFM
1.4.4 Doping of ZnO
n-doping p-doping
1.4.5 Magneto-transport properties
1.4.6 ZnO as TCE
2 Experimental
2.1 Samples fabrication
2.1.1 Glass substrates involved
2.1.2 Graphene
2.1.3 Zinc oxide
2.2 Characterization methods
2.2.1 Optical microscope
2.2.2 Atomic Force Microscopy
2.2.3 Raman Spectroscopy
The principles of Raman scattering
Raman microscopy in 2D materials
2.2.4 X-ray diraction
2.3 Device fabrication
2.3.1 Van der Pauw method
2.3.2 Contact deposition
2.3.3 Sample shaping
2.4 Electronic transport measurements setup
3 Space Charge Doping
3.1 The principles of space charge doping
3.1.1 Glass atomic structure
3.1.2 Ionic drift
3.2 Space charge doping applied to graphene
3.2.1 Fabrication of the graphene samples
CVD graphene
Anodic Bonded graphene
Contact deposition and shaping
3.2.2 Results
Ambipolar doping
Fine doping and doping limit
Reversibility
Substrate surface quality
Transmittance
Quality of the doped samples
3.3 Comparison with other doping methods
3.4 Control measurement on quartz
3.5 Conclusions on space charge doping
4 Ultra-high doping of ZnO1􀀀x thin lms
4.1 ZnO1􀀀x device fabrication
4.1.1 Zinc oxide deposition on glass
4.1.2 X-ray diraction, AFM and transmittance
4.1.3 Sample shaping and contact deposition
4.2 Space Charge Doping applied to the ZnO thin lm
4.2.1 Fine control of doping in the thin lm
4.2.2 Carrier scattering mechanism
Lattice phonon scatterimg
Grain boundary scattering
Ionized impurity scattering
4.3 Variable Range Hopping and mobility edge
4.3.1 Variable range hopping in ZnO thin lms
4.3.2 Mobility edge
4.3.3 2D nature of the doped lm
4.4 Conclusions on space charge doping of ZnO
5 Magneto-transport and spin orbit coupling
5.1 Weak localization
5.1.1 Backscattering
5.1.2 Temperature dependence of the conductivity
5.2 Magneto-conductivity
5.2.1 Theoretical considerations
Eect of the weak localization
In uence of spin-orbit coupling on the magneto-conductivity
5.2.2 Magneto-conductivity of ZnO
WL to WAL transition as a function of temperature .
WL to WAL transition as a function of carrier concentration
Considerations on the characteristic transport lengths
5.3 Origin of the spin-orbit coupling
5.3.1 D’Yakonov-Perel’ mechanism
5.3.2 Rashba eect
5.3.3 Elliott-Yafet mechanism
5.4 Considerations on the metal-insulator transition
5.5 Conclusions of the magneto-transport in ZnO
6 Conclusions and perspectives
List of abbreviations and symbols