1.2. Outline of the dissertation………6

i

C ^ONTENTS

1. General Introduction ………1

1.1. Motivation………1

1.2. Outline of the dissertation………6

2. Properties of graphene………..8

2.1. The Graphene Structure………...8

2.2. Structural properties of Graphene……….9

2.3. The electronic band structure of the graphene lattice………..12

2.4. Carrier statistics and mobility in graphene………...17

2.5. Some interesting properties……….22

2.5.1.1. Stability in two dimensions………...22

2.5.1.2. Anomalous Integer Quantum Hall Effect………24

2.5.1.3. Klein Paradox………..27

2.5.1.4. DOS for Graphene and Semiconductors……….31

2.6. Optical properties………...32

3. Graphene production and graphene characterization techniques………..35

3.1. Introduction………...35

3.2. Graphene production...………...35

3.3. Experimental Method for graphene fabrication ………..…………37

3.4. Techniques for the detection and characterization of graphene flakes……….42

3.4.1.1. Optical microscopy……… ……….43

3.4.1.2. Study of contrast for rapid identification of graphene………..43

3.4.1.3. Raman Scattering……….49

3.5. Analysis of Contrast and Raman Spectra of Graphene on different substrate………..55

3.5.1.1. Study of best filter………...56

3.5.1.2. Contrast and Raman of Graphene exfoliated on Glass 100um………...58

3.5.1.3. Contrast and Raman of Graphene exfoliated on ITO 40nm/1mm Glass…………63

3.5.1.4. Contrast and Raman of Graphene exfoliated on Diamond 40_50nm/SiO

/p-Si………...65

3.6. Processing the flakes………...68

ii

4. Graphene-based field-effect transistors………...70

4.1. Graphene for Nanotransistors………70

4.1.1.1. State of the art in graphene FET performance……….71

4.2. Contact and edge effects in graphene devices………..74

4.2.1.1. Introduction………74

4.2.1.2. Sample preparation and measurement setup………75

4.2.1.3. Results and discussion………...77

4.3. Origin of anomalies in GFETs transfer characteristic………...81

4.3.1.1. Introduction………....81

4.3.1.2. Transfer Characteristics in GFETs with Cr/Au contacts….………...82

4.3.1.3. Transfer Characteristics in GFETs with Ni, Ti contacts……….……...91

4.4. Conclusion………...93

5. Field Emission from graphene……….………..94

5.1. Introduction………....94

5.2. Theory of the Field Emission………..94

5.3. Device fabrication and measurements set up………...95

5.4. Results and analysis……….97

6. Fabrication and Optical measurements of Graphene – Plasmonic Nanostructures………104

6.1. Introduction………...104

6.2. Surface Plasmons Photonics………..105

6.2.1.1. Electron Oscillation and dispersion relation………...105

6.2.1.2. Methods and Optical Excitation of Plasmons………106

6.2.1.3. Experimental Setup for detecting the SPR and measurements…………...111

6.2.1.4. Simulation of Reflectivity Spectra of the SP………...115

6.3. Localized Surface Plasmons………...118

6.4. Graphene Plasmonics………....122

6.4.1.1. Introduction………..………122

6.4.1.2. Graphene as a substrate for plasmonic nanoparticles……….124

6.4.1.3. Periodic arrays of metallic nanoparticles produced on graphene by electron beam Lithography………...125

6.4.1.4. Measurements Setup………...128

6.4.1.5. Results and Analysis………...131

iii Conclusion

Acknowledgements

References