Xenes: 2D Synthetic Materials Beyond Graphene

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Half Title
Xenes: 2D Synthetic Materials Beyond Graphene
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Contents
About the Editors
List of contributors
Preface
Introduction
	Two-dimensional materials beyond graphene: the rise of the Xenes
		Borophene and gallenene
		Silicene, germanene, stanene, and plumbene
		Phosphorene, arsenene, antimonene, and bismuthene
	A brief overview of the Xenes from the periodic table
		Selenene and tellurene
	Xenes toward nanotechnologies
	Conclusions
	References
1. Silicene
	1.1 Introduction
	1.2 Historical background: the Schottky problem
	1.3 Silicene: the concept
	1.4 Exotic phases of silicene and their topological electronic properties—theory
	1.5 Discovery of one-dimensional silicon nanoribbons
	1.6 The birth of two-dimensional silicene
	1.7 Hydrogenation of the canonical 3 3 3/4 3 4 silicene phase on A
	1.8 Other allotropic phases of silicene on Ag(1 1 1) and multilayer
	1.9 Reactivity and adsorption on silicene, silicene on other substrates, and silicene by wet chemistry
	1.10 Exotic variants of silicene: penta-silicene nanoribbons and kagome silicene
		1.10.1 Penta-silicene nanoribbons
		1.10.2 Kagome silicene
	1.11 Properties, applications, and perspectives
	1.12 Conclusion
	Note
	References
2. Germanene
	2.1 Introduction two-dimensional Dirac materials
	2.2 Synthesis of germanene
		2.2.1 Introduction
		2.2.2 Synthesis of germanene
			2.2.2.1 Germanene on Pt(1 1 1)
			2.2.2.2 Germanene on Au(1 1 1)
			2.2.2.3 Germanene on Ge2Pt
			2.2.2.4 Germanene on Al(1 1 1)
			2.2.2.5 Germanene on molybdenum disulfide (MoS2)
			2.2.2.6 Germanene on Cu(1 1 1)
			2.2.2.7 Germanene on hexagonal AIN/Ag(1 1 1)
			2.2.2.8 Germanene on Sb(1 1 1)
			2.2.2.9 Germanene on highly oriented pyrolytic graphite
			2.2.2.10 Germanene on Ag(1 1 1)
	2.3 Structural and electronic properties of germanene
	2.4 Anomalous quantum Hall effect and quantum spin Hall effect
		2.4.1 Anomalous quantum Hall effect
		2.4.2 Quantum spin Hall effect
	2.5 Bandgap opening in germanene
		2.5.1 Electric-field-induced bandgap opening
		2.5.2 Bandgap opening by coupling to a substrate and adsorption or or intercalation of atoms or molecules
	2.6 Bilayer germanene and twisted bilayer germanene
	2.7 Summary
	References
3. Stanene and Plumbene
	3.1 Introduction: tin and stanene, lead and plumbene
	3.2 The theoretical prediction of stanene and plumbene
	3.3 Theoretical prediction for stanene to be a two dimensional topological insulator
		3.3.1 Stanene as quantum spin Hall insulator described by Kane-Mele model
		3.3.2 Decorated stanene as quantum spin Hall insulator described by Bernevig-Hughes-Zhang model
		3.3.3 Modified stanene as quantum anomalous Hall insulator
		3.3.4 Theoretical prediction for stanene to be a two-dimensional Ising superconductor
	3.4 The synthesis and characterization of stanene
		3.4.1 Epitaxial growth of stanene
		3.4.2 Topological band inversion in ultraflat stanene
		3.4.3 Two-dimensional Ising superconductivity in few layer stanene
	3.5 The synthesis and characterization of plumbene
	3.6 Perspectives on the applications of stanene and plumbene
	References
4. Borophene
	4.1 Introduction
	4.2 Theoretical aspects of borophene
	4.3 Synthesis of borophene
		4.3.1 Borophenes on Ag(111), (110), and (100)
		4.3.2 Borophene on Cu(111)
		4.3.3 Borophene on Al(111)
		4.3.4 Borophene on Ir(111)
		4.3.5 Liquid-phase exfoliation
		4.3.6 Hydrogenated borophene (borophane)
	4.4 Physical properties of borophene
		4.4.1 Mechanical properties
		4.4.2 Metallicity
		4.4.3 Dirac cones and Dirac nodal lines
		4.4.4 Superconductivity
		4.4.5 Optical properties
	4.5 Perspective
	References
5. Gallenene
	5.1 Evidence of two-dimensionality in bulk gallium
	5.2 Evidence of two-dimensionality in gallium nanostructures
	5.3 Experimental discovery
	5.4 Electronic properties
	5.5 Thermal stability
	5.6 How unique is gallenene?
	5.7 Properties and applications of gallenene
	Acknowledgments
	References
6. Phosphorene
	6.1 Introduction
	6.2 Properties of two-dimensional black phosphorus
		6.2.1 Crystal and band structure
		6.2.2 Optical properties
		6.2.3 Thermoelectric properties
	6.3 Applications
		6.3.1 Electronic devices
		6.3.2 Optoelectronic devices
		6.3.3 Bioapplications
	6.4 Fabrication
		6.4.1 Bulk crystals
		6.4.2 Few-/single-layer Black phosphorus
			6.4.2.1 Top-down
			6.4.2.2 Bottom-up growth
		6.4.3 Blue phosphorene
	6.5 Functionalization
		6.5.1 Surface functionalization
		6.5.2 Bandgap engineering
		6.5.3 Defects engineering
	6.6 Oxidation and surface protection
		6.6.1 Oxidation mechanism
		6.6.2 Surface protection
			6.6.2.1 Encapsulation
			6.6.2.2 Covalent functionalization
			6.6.2.3 Noncovalent functionalization
	6.7 Conclusion and outlook
	Acknowledgments
	References
7. Arsenene and Antimonene
	7.1 Introduction
	7.2 Arsenic and antimony allotropes
		7.2.1 Arsenic
		7.2.2 Antimony
	7.3 Two-dimensional arsenene and antimonene
		7.3.1 Fundamentals
		7.3.2 “Top-down” methods
		7.3.3 “Bottom-up” methods
	7.4 Doping of arsenene and antimonene
	7.5 Applications and future prospects of arsenene and antimonene
	7.6 Conclusion
	Acknowledgement
	References
8. Bismuthene
	8.1 Introduction
	8.2 Structure and properties of two-dimensional bismuth
		8.2.1 Atomic structure
		8.2.2 Band structure
		8.2.3 Fundamental properties
			8.2.3.1 Mechanical properties
			8.2.3.2 Optical properties
			8.2.3.3 Thermoelectric properties
			8.2.3.4 Topological properties
	8.3 Preparation of two-dimensional bismuth
		8.3.1 Physical vapor deposition
		8.3.2 Wet chemical methods
		8.3.3 Exfoliation methods
	8.4 Characterization of two-dimensional bismuth
		8.4.1 Structure characterization
		8.4.2 Morphology characterization
		8.4.3 Electrical properties
	8.5 Applications of two-dimensional bismuth
		8.5.1 Field-effect transistors
		8.5.2 Thermoelectrics
		8.5.3 Photodetectors
		8.5.4 Batteries
	8.6 Summary
	References
9. Selenene and Tellurene
	9.1 Introduction
	9.2 Selenene
		9.2.1 Synthesis methods
			9.2.1.1 Biomolecule-assisted hydrothermal synthesis
			9.2.1.2 Porous template-assisted method
			9.2.1.3 Physical vapor deposition
		9.2.2 Physical properties
			9.2.2.1 Optical properties
			9.2.2.2 Thermal properties and stability
			9.2.2.3 Electrical properties
		9.2.3 Applications
			9.2.3.1 Field-effect transistors
			9.2.3.2 Photoelectric devices
			9.2.3.3 Synaptic transistors
	9.3 Tellurene
		9.3.1 Synthesis methods
			9.3.1.1 Pulsed laser deposition
			9.3.1.2 Physical vapor deposition
			9.3.1.3 Magnetron sputtering
			9.3.1.4 Liquid-phase exfoliation
			9.3.1.5 Thermal evaporation
			9.3.1.6 Solution-based growth
			9.3.1.7 Encapsulation in nanotubes
		9.3.2 Physical properties
			9.3.2.1 Electrical properties
			9.3.2.2 Topological properties
			9.3.2.3 Optical properties
		9.3.3 Electronic applications
			9.3.3.1 Field-effect transistors
			9.3.3.2 Thermoelectric devices
	9.4 Conclusions
	References
10. Technical evolution for the identification of Xenes: from microscopy to spectroscopy
	10.1 Introduction
	10.2 Working principles of scanning tunneling microscopy and angular-resolved photoemission spectroscopy
		10.2.1 Scanning tunneling microscopy
		10.2.2 Angular-resolved photoemission spectroscopy
	10.3 Applications of scanning tunneling microscopy and angular-resolved photoemission spectroscopy in Xenes
		10.3.1 Silicene and germanene
			10.3.1.1 Topographic and electronic structure of silicene and germanene
			10.3.1.2 Quasiparticle interference in silicene
		10.3.2 Borophene
		10.3.3 Stanene
		10.3.4 Bismuthene
		10.3.5 Phosphorene
		10.3.6 Antimonene, arsenene, and tellurene
	10.4 Emerging techniques used in Xenes
		10.4.1 Raman spectroscopy studies on Xenes
		10.4.2 Atomic force microscopy
		10.4.3 Transmission electron microscopy
		10.4.4 X-ray photoemission spectroscopy
		10.4.5 Spin-resolved angular-resolved photoemission spectroscopy
		10.4.6 Auger electron spectroscopy and low-energy electron diffraction and reflection high-energy electron diffraction
	References
11. Chemical methods for Xenes
	11.1 Introduction
	11.2 Surface functionalization metrology
	11.3 Analogy of Si(111) and Ge(111) surface functionalization
	11.4 Chemical treatments and reactivity of Si, Ge, Sn Xenes
	11.5 Topotactic transformations of Zintl phases in the synthesis of functionalized Xenes
		11.5.1 Functionalized silicene analogs from topotactic transformations of CaSi2
		11.5.2 Functionalized germanene from topotactic transformations of CaGe2
		11.5.3 Functionalized Sn Xenes from the topotactic transformations of Sn-containing Zintl phases
		11.5.4 Organic-functionalized Xenes via topotactic functionalization of Zintl phases with haloalkanes
	11.6 Ligand substitution reactions of functionalized Si and Ge Xenes
		11.6.1 SiH to SiR via hydrosilylation
		11.6.2 GeH to GeR via hydrogermylation
		11.6.3 SiH to SiNR via amination
		11.6.4 SiH to SiH4Ph via Grignard chemistry
	11.7 Covalent modification of other Xenes
	11.8 Functionalization-induced changes in thermal and electronic properties of group 14 Xenes
		11.8.1 Functionalization-induced changes in electronic structure
		11.8.2 Functionalization-induced changes in carrier mobilities
		11.8.3 Signatures of amorphization and functionalization induced changes in conductivity and thermal stability
		11.8.4 Functionalization-induced changes in water absorption
	11.9 Conclusion
	References
12. Topological physics of Xenes
	12.1 Two-dimensional topological insulators
		12.1.1 Two typical models for quantum spin Hall insulators
		12.1.2 Topological Z2 invariant
		12.1.3 Quantum spin Hall insulators in Xenes
	12.2 Quantum anomalous Hall effect in Xene
		12.2.1 Introduction to the quantum anomalous Hall effect
		12.2.2 Theoretical models of quantum anomalous Hall states in Xene
		12.2.3 Realization of the quantum anomalous Hall states in Xenes
	12.3 Topological superconductivity and Ising superconductivity
		12.3.1 General introduction
		12.3.2 Type-II Ising superconductivity
		12.3.3 Topological superconductivity
		12.3.4 Other research progresses
	12.4 Thermoelectric properties in Xenes
	12.5 Summary and outlook
	References
13. Optical properties of Xenes
	Abbreviations
	13.1 Introduction
	13.2 Theoretical methods
		13.2.1 Reflectance, transmittance, and absorbance
		13.2.2 Optical conductivity and the superlattice method
		13.2.3 Ab initio approaches: from single particles to quasiparticles
			13.2.3.1 Ground-state properties: the density functional theory
			13.2.3.2 Quasiparticles: the GW approximation
			13.2.3.3 Excitonic effects: the Bethe Salpeter equation
	13.3 Results
		13.3.1 Freestanding Xenes
			13.3.1.1 Graphene
			13.3.1.2 Silicene
			13.3.1.3 Germanene
			13.3.1.4 Stanene
			13.3.1.5 Plumbene
			13.3.1.6 Universal infrared absorbance of Group-IV crystals
			13.3.1.7 Silicongraphene
			13.3.1.8 Spin orbit corrections
		13.3.2 Hydrogenated Xenes: the Xanes
		13.3.3 Beyond the freestanding case: substrate effects
			13.3.3.1 Silicene on sapphire
			13.3.3.2 Silicene on Ag surfaces
	13.4 Summary and conclusions
	Acknowledgments
	References
14. Two-dimensional magnetism in Xenes
	14.1 Introduction
	14.2 Theoretical predictions of magnetism in Xenes
	14.3 Intrinsic magnetism in Xene multilayer three dimensional compounds
	14.4 Two-dimensional ferromagnetism in silicene materials
	14.5 Two-dimensional ferromagnetism in germanene materials
	14.6 Electron transport in two-dimensional magnetic Xene compounds
	14.7 Extension of two-dimensional ferromagnetism to graphene
	14.8 Conclusion
	Acknowledgments
	References
15. Xene heterostructures
	15.1 Introduction
	15.2 Xene homostructures
	15.3 Xene heterostructures
	15.4 Challenges, bottlenecks, potential and perspectives
	Acknowledgement
	References
16. Integration paths for Xenes
	16.1 Introduction
		16.1.1 Major players from a device perspective
		16.1.2 Growth techniques and functionalization of Xenes
		16.1.3 Application of Xene devices
		16.1.4 Challenges in device fabrication
	16.2 Review of existing electronic devices
		16.2.1 Group 14 devices
			16.2.1.1 Silicene: silicene encapsulated delamination with native electrodes technique
			16.2.1.2 Seamless silicene encapsulated delamination with native electrodes method
			16.2.1.3 Universal Xene encapsulation, decoupling and operation approach
			16.2.1.4 Heterostructure devices
			16.2.1.5 Germanene field-effect transistors
		16.2.2 Group 15 (pnictogens) devices
			16.2.2.1 Phosphorene and black phosphorus devices
				Black phosphorus/phosphorene
			16.2.2.2 Arsenene, antimonene, and bismuthene devices
		16.2.3 Group 16 (chalcogens) devices
			16.2.3.1 Selenene and tellurene field-effect transistors
	16.3 Current and future applications of Xenes
		16.3.1 Photonics devices
		16.3.2 Biomedical devices
		16.3.3 Topology-based electronic devices
		16.3.4 Memory devices
		16.3.5 Xene-based junctions
	16.4 Perspectives on integration of Xenes with silicon
	16.5 Concluding remarks
	References
	Further reading
Index
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