Spatial profile of the photocurrent

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Table of contents

1 Introduction 
1.1 General context
1.2 State-of-the-art
1.2.1 THz sources
1.2.2 THz amplifiers
1.2.3 THz amplitude modulators
1.2.4 THz waveguides
1.3 Graphene for THz technology
1.3.1 Electronic band structure of graphene
1.4 Thesis outline
2 Graphene/hBN phototransistors: transport properties 
2.1 Introduction
2.2 Fabrication of the graphene/hBN phototransistors
2.3 Experimental set-up for transport measurements
2.4 The current properties in biased graphene
2.5 Dark current-bias characteristics of the graphene/hBN phototransistors .
2.6 Conclusion
3 Photoresponse of graphene-hBN photo-transistors under mid-infrared illumination 
3.1 Photo-transport in biased graphene/hBN phototransistor
3.1.1 Experimental set-up
3.1.2 Spatial profile of the photocurrent
3.1.3 Competing mechanisms for photocurrent
3.2 Linear photoresponse in biased graphene/hBN phototransistor
3.2.1 Photocurrent–bias characteristics
3.2.2 Photoexcited carrier density
3.2.3 Carrier lifetime
3.2.4 Responsivity
3.2.5 Influence of light polarization
3.3 Nonlinear photoresponses in biased graphene/hBN phototransistor
3.3.1 Non-linear regime in V ∗ DS
3.3.2 Emission of Hyperbolic Phonon Polaritons
3.3.3 Non-linear regime in Pinc
3.3.4 Photoexcited carrier density
3.3.5 Full photoconductive response including all regimes
3.4 Conclusion and Perspectives
4 Graphene based metal-dielectric waveguide 
4.1 Introduction
4.2 Description of the graphene-coupled dielectric-metal waveguides
4.3 Mode analysis of waveguides based on FEM method
4.3.1 Full vector mode analysis in 2D
4.3.2 Boundary conditions
4.3.3 Dispersion relation of the fundamental modes
4.3.4 Graphene coupled to the hybrid dielectric-metal waveguide
4.4 Conclusion
5 THz characterization of the graphene coupled hybrid waveguides 
5.1 Fabrication and process characterization
5.1.1 Characterization of the graphene coverage
5.1.2 Electrical characterization
5.2 THz characterization of the devices
5.2.1 THz time-domain spectroscopy system
5.2.2 THz characterization of the hybrid waveguides
5.2.3 Interpretation based on interference effect
5.3 Conclusion and perspectives
6 General conclusion and perspectives 
A Appendix 
B Fabrication of waveguide samples 
B.1 The strategy uesd in mapping Raman spectroscopy
Bibliography