Thạc Sĩ 2D materials for nanoelectronics: A first-principles investigation

Table of Contents
Acknowledgements i
Abstract v
Publications viii
List of Tables x
List of Figures xi
1 Introduction 1
1.1 Physical limits of Si-based MOSFETs scaling 1
1.2 2D materials and 2D materials based nanoelectronics 3
1.3 Challenges in 2D materials based nanoelectronics 5
1.3.1 2D materials and metal contact 7
1.3.2 2D materials heterostructure . 9
1.3.3 Emerging 2D materials 10
1.4 Objectives and scope of the study . 11
2 Methodology 14
2.1 Density functional theory . 14
ii2.1.1 Many-particle Schr¨odinger equation . 14
2.1.2 Born-Oppenheimer approximation 15
2.1.3 Hartree-Fock approximation . 16
2.1.4 Density functional theory . 18
2.1.5 Exhcange-correlation functionals 20
2.1.6 Bloch’s theorem and supercell approximation 22
2.1.7 Brillouin zone sampling . 23
2.1.8 Plane-wave basis sets . 24
2.1.9 Pseudopotential approximation 25
2.2 Nonequilibrium Green’s function method 27
2.3 VASP and ATK software packages 29
3 Efficient spin injection into graphene with tunnel barriers 31
3.1 Introduction 31
3.2 Computational details . 33
3.3 Results and disscussion 34
3.3.1 Atomic geometry . 34
3.3.2 Transport calculations 36
3.3.3 Electronic structure calculations . 44
3.4 Summary . 48
4 Transport properties of monolayer MoS 2 /metal junctions 50
4.1 Introduction 50
4.2 Computational details . 51
4.3 Results and discusstion 53
4.4 Summary . 62
iii5 Strain and electric field tunable direct band gap of MS 2 /SiC bilayers 64
5.1 Introduction 64
5.2 Computational details . 65
5.3 Results and discussion 66
5.4 Summary . 76
6 Giant Stark effect on band gaps of phosphorene nanoribbons 78
6.1 Introduction 78
6.2 Computational details . 80
6.3 Results and discussion 80
6.4 Summary . 93
7 Concluding remarks 95
7.1 Conclusions 95
7.2 Future works . 98
References 100
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