报告二维超导体

1、Two-dimensional semiconductor,Yu Ye (叶堉） ye_yu ,Outlook,Electronics of 2D materials 1. Scaling of the semiconductor generation 2. Electronic engineering of TMDC Strong confinement of monolayer TMDCs Indirect to direct band gap transition Excitonic transitions Inversion symmetry breaking of monolayer

2、 TMDCs 1. Nonlinearity (Piezo, SHG) 2. Nonequivalent valley index,Insulator, semiconductor and conductor,Semiconductor and human daily life,Point-contact transistor-first transistor ever made,The first point-contact transistor.,Technology generation-need broad exploration,45 nm 2007,22 nm 2011,32 nm

3、 2009,14 nm 2013,10 nm 2015,7 nm 2017,Beyond 2020,QW III-V device,Carbon Nanotube 1 nm diameter,Graphene 1 atom thick,Nature Nanotechnology 6, 147 (2011),Why 2D semiconductor,From Wiki,Molybdenite,Nature Nanotech. 7, 699 (2012),Different stacking phases of the MoS2,Cleaved by blade and tweezers,Sing

4、le-layer MoS2 transistors,Nature Nanotechnology 6, 147 (2011).,MoS2 transistors with 1 nm gate lengths,Science 354, 99 (2016).,Wafer scale monolayer MoS2,Nature 520, 656 (2015),Carbon nanotube computer,Inorganic nanowire Carbon nanotubes,Precisely place and orientation Complex fabrication techniques

5、,Nature 501, 526 (2013),Self-assembly graphene-MoS2-graphene heterostructures,Nature Nanotechnolgoy DOI: 10.1038/NNANO.2016.115.,TEM characteristics,Nature Nanotechnolgoy DOI: 10.1038/NNANO.2016.115.,Transistor of graphene/MoS2/graphene,Nature Nanotechnolgoy DOI: 10.1038/NNANO.2016.115.,Self-assembl

6、ed 2D circuit,Nature Nanotechnolgoy DOI: 10.1038/NNANO.2016.115.,Outlook,Electronics of 2D materials 1. Electronic engineering of TMDC 2. Transistors built on black phosphorous Strong confinement of monolayer TMDCs Indirect to direct band gap transition Excitonic transitions Inversion symmetry break

7、ing of monolayer TMDCs 1. Nonlinearity (Piezo, SHG) 2. Nonequivalent valley index,Bulk Quadrilayer Bilayer monolayer,Atomic structure and electronic band structure of MoS2,Nano Lett. 2010, 10, 12711275,PL and quantum yield of MoS2,PRL 105, 136805 (2010),21,Excitation 488 nm Detection 640nm,Si/MoS2 p

8、n heterojunction,22,APL 104, 193508 (2014),Homojunction LEDs,Nature Nanotech. 9, 268 (2014) Nature Nanotech. 9, 262 (2014) Nature Nanotech. 9, 257 (2014),Homojunction LEDs,Nature Nanotech. 9, 268 (2014) Nature Nanotech. 9, 262 (2014) Nature Nanotech. 9, 257 (2014),2D exciton,PRL 113, 076802 (2014),C

9、harles Kittel, Introduction to solid state physics,Monolayer WS2 Rydberg series,PRL 113, 076802 (2014),Binding energy: 320 meV,Probing dark state in monolayer WS2,Binding energy: 700 meV,Nature 513, 214 (2014).,First-principle calculation,Nature 513, 214 (2014).,Binding energy: 700 meV,Control of ne

10、utral and charged excitons emission,Nature Comm. 4, 1474 (2013).,Control of neutral and charged excitons emission,Nature Comm. 4, 1474 (2013).,Higher modulation bandwidth Small emission linewidth,High Q cavity Strong confinement factor,Monolayer WS2 excitonic laser,Nature Photonics 9, 733 (2015).,WG

11、M modes,190 fs, 80 MHz, excitation Q2600,Nature Photonics 9, 733 (2015).,Observation of monolayer lasing,Nature Photonics 9, 733 (2015).,Long wavelength WGM,Nature Photonics 9, 733 (2015).,Characterizations of 2D excitonic lasing,Nature Photonics 9, 733 (2015).,Strong confinement of monolayer TMDC,E

12、lectronic structure evolution: indirect band gap to direct band gap. Direct band gap of the monolayer TMDC enables light emission. Large exciton binding energy: robust excitonic phenomena even at room temperature. Large trion binding energy.,Outlook,Electronics of 2D materials 1. Electronic engineer

13、ing of TMDC 2. Transistors built on black phosphorous Strong confinement of monolayer TMDCs Indirect to direct band gap transition Excitonic transitions Inversion symmetry breaking of monolayer TMDCs 1. Nonlinearity (Piezo, SHG) 2. Nonequivalent valley index,Symmetry for phase and layer dependent,Bu

14、lk 3R,Bulk or even-layers 2H,Monolayer,With inversion symmetry Indirect bandgap,Without inversion symmetry Indirect bandgap,Without inversion symmetry Direct bandgap,arXiv: 1304.4289v1 (2013),Angular dependent SHG of monolayer MoS2,WiKi,SHG determines the grain size,Science 344, 488 (2014),Science 3

15、44, 488 (2014),SHG mapping,SHG vs TEM,DF-STEM,Layer number dependence of SHG,Nano Lett. 13, 3329 (2013).,SHG from 3R stacking phase,Light: Sci. Nature Nanotech. 7, 494 (2012); Nature Comm. 3, 887 (2012).,Circularly polarized light boosts valleytronics,Chiral light-emitting transistor,Science 344, 72

16、5 (2014).,Triangular warping,arXiv: 1410.0615v1,Electrical control of circularly polarized emission,Science 344, 725 (2014).,Light: Sci. & Appl. 6, e124 (2014).,Electrical valley generation and detection in monolayer TMDCs,TMDC: long lifetime of polarized hole and spin-valley locking. Ferromagnetic

17、semiconductor: conductivity matching and high spin injection efficiency.,Nat. Nanotech. 11, 598, (2016).,WS2/(Ga, Mn)As heterostructure,No defect emission. Suppression of B exciton emission.,Nat. Nanotech. 11, 598, (2016).,Electrical Valley excitation in WS2,Outward B,Inward B, = -14.8%, = 16.2%,Nat

18、. Nanotech. 11, 598, (2016).,Magnetic field dependent,Nat. Nanotech. 11, 598, (2016).,Valley exciton generation efficiency,Non-perfect spin polarization. Valley scattering. Joule heating.,Nat. Nanotech. 11, 598, (2016).,Valley contrasting Berry curvature,PRL 99, 236809 (2007).,The valley Hall effect,Science 344, 1489 (2