REVIEWS

Contact engineering for two-dimensional semiconductors

Peng Zhang1, Yiwei Zhang1, Yi Wei2, Huaning Jiang1, Xingguo Wang1 and Yongji Gong1,

+ Author Affiliations

 Corresponding author: Yongji Gong, Email: yongjigong@buaa.edu.cn

PDF

Turn off MathJax

Abstract: Two-dimensional (2D) layered materials, including graphene, black phosphorus (BP) and transition metal dichalcogenide (TMD) such as molybdenum disulfide (MoS2), tungsten diselenide (WSe2), have attracted increasing attention for the application in electronic and optoelectronic devices. Contacts, which are the communication links between these 2D materials and external circuitry, have significant effects on the performance of electronic and optoelectronic devices. However, the performance of devices based on 2D semiconductors (SCs) is often limited by the contacts. Here, we provide a comprehensive overview of the basic physics and role of contacts in 2D SCs, elucidating Schottky barrier nature and Fermi level pinning effect at metal/2D SCs contact interface. The progress of contact engineering, including traditional metals contacts and metallic 2D materials contacts, for improving the performance of 2D SCs based devices is presented. Traditional metal contacts, named 3D top and edge contacts, are discussed briefly. Meanwhile, methods of building 2D materials contacts (2D top contact and 2D edge contact) are discussed in detail, such as chemical vapor deposition (CVD) growth of 2D metallic material contacts, phase engineered metallic phase contacts and intercalation induced metallic state contacts. Finally, the challenges and opportunities of contact engineering for 2D SCs are outlined.

Key words: two-dimensional materialscontact engineeringSchottky barrierFermi level pinningheterostructures



[1]
Schaller R. Moore's law: past, present and future. IEEE Spectrum, 1997, 34(6), 52 doi: 10.1109/6.591665
[2]
Frank D J, Dennard R H, Nowak E, et al. Device scaling limits of Si MOSFETs and their application dependencies. Proc IEEE, 2001, 89(3), 259 doi: 10.1109/5.915374
[3]
Sarkar D, Xie X J, Liu W, et al. A subthermionic tunnel field-effect transistor with an atomically thin channel. Nature, 2015, 526, 91 doi: 10.1038/nature15387
[4]
Arnold A J, Razavieh A, Nas J R, et al. Mimicking neurotransmitter release in chemical synapses via hysteresis engineering in MoS2 transistors. ACS Nano, 2017, 11(3), 3110 doi: 10.1021/acsnano.7b00113
[5]
Gong Y J, Shi G, Zhang Z H, et al. Direct chemical conversion of graphene to boronand nitrogen-and carbon-containing atomic layers. Nat Common, 2014, 5, 3193 doi: 10.1038/ncomms4193
[6]
Xie Y L, Lian B, Jäck B, et al. Spectroscopic signatures of many-body correlations in magic-angle twisted bilayer graphene. Nature, 2019, 572, 101 doi: 10.1038/s41586-019-1422-x
[7]
Li L F, Liu W, Gao A Y, et al. Plasmon excited ultrahot carriers and negative differential photoresponse in a vertical graphene van der Waals heterostructure. Nano Lett, 2019, 19(5), 3295 doi: 10.1021/acs.nanolett.9b00908
[8]
Novoselov K S, Geim A K, Morozov S V, et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature, 2005, 438, 197 doi: 10.1038/nature04233
[9]
Zhang Y B, Tan Y W, Stormer H L, et al. Experimental observation of the quantum Hall effect and Berry's phase in graphene. Nature, 2005, 438, 201 doi: 10.1038/nature04235
[10]
Lee C, Wei X D, Kysar J W, et al. Measurement of the elastic properties and intrinsic strength of monolayer graphene. Science, 2008, 321(5887), 385 doi: 10.1126/science.1157996
[11]
Liu Y P, Yudhistira I, Yang M, et al. Phonon-mediated colossal magnetoresistance in graphene/black phosphorus heterostructures. Nano Lett, 2018, 18(6), 3377 doi: 10.1021/acs.nanolett.8b00155
[12]
Huang S Y, Zhang G W, Fan F R, et al. Strain-tunable van der Waals interactions in few-layer black phosphorus. Nat Common, 2019, 10, 2447 doi: 10.1038/s41467-019-10483-8
[13]
Chaudhary K, Tamagnone M, Rezaee M, et al. Engineering phonon polaritons in van der Waals heterostructures to enhance in-plane optical anisotropy. Sci Adv, 2019, 5(4), eaau7171 doi: 10.1126/sciadv.aau7171
[14]
Kim J M, Baik S S, Ryu S H, et al. Observation of tunable band gap and anisotropic Dirac semimetal state in black phosphorus. Science, 2015, 349(6249), 723 doi: 10.1126/science.aaa6486
[15]
Peng R M, Khaliji K, Youngblood N, et al. Midinfrared electro-optic modulation in few-layer black phosphorus. Nano Lett, 2017, 17(10), 6315 doi: 10.1021/acs.nanolett.7b03050
[16]
Liu Z, Gong Y G, Zhou W, et al. Ultrathin high-temperature oxidation-resistant coatings of hexagonal boron nitride. Nat Commun, 2013, 4, 2541 doi: 10.1038/ncomms3541
[17]
Wu E X, Xie Y, Zhang J, et al. Dynamically controllable polarity modulation of MoTe2 field-effect transistors through ultraviolet light and electrostatic activation. Sci Adv, 2019, 5(5), eaav3430 doi: 10.1126/sciadv.aav3430
[18]
Park H J, Tay R Y J, Wang X, et al. Double-spiral hexagonal boron nitride and shear strained coalescence boundary. Nano Lett, 2019, 19(7), 4229 doi: 10.1021/acs.nanolett.8b05034
[19]
Song L, Ci L J, Lu H, et al. Large scale growth and characterization of atomic hexagonal boron nitride layers. Nano Lett, 2010, 10(8), 3209 doi: 10.1021/nl1022139
[20]
Ci L J, Song L, Jin C J, et al. Atomic layers of hybridized boron nitride and graphene domains. Nat Mater, 2010, 9, 430 doi: 10.1038/nmat2711
[21]
Gong Y G, Lin J H, Wang X L, et al. Vertical and in-plane heterostructures from WS2/MoS2 monolayers. Nat Mater, 2014, 13, 1135 doi: 10.1038/nmat4091
[22]
Gong Y G, Liu Z, Lupini A R, et al. Band gap engineering and layer-by-layer mapping of selenium doped molybdenum disulfide. Nano Lett, 2014, 14(2), 442 doi: 10.1021/nl4032296
[23]
Ma Y, Ajayan P M, Gong Y J, et al. Recent advances in synthesis and applications of 2D junctions. Small, 2018, 14(38), 1801606 doi: 10.1002/smll.201801606
[24]
Lin Y C, Li S S, Komsa H P, et al. Revealing the atomic defects of WS2 governing its distinct optical emissions. Adv Funct Mater, 2017, 28(4), 1704210 doi: 10.1002/adfm.201704210
[25]
Sun L F, Leong W S, Yang S Z, et al. Concurrent synthesis of high-performance monolayer transition metal disulfdes. Adv Funct Mater, 2017, 27(15), 1605896 doi: 10.1002/adfm.201605896
[26]
Zhou Y, Jang H J, Woods J M, et al. Direct synthesis of large-scale WTe2 thin films with low thermal conductivity. Adv Funct Mater, 2017, 27(8), 1605928 doi: 10.1002/adfm.201605928
[27]
Zhao Y D, Qiao J S, Yu P, et al. Extraordinarily strong interlayer interaction in 2D layered PtS2. Adv Mater, 2017, 28(12), 2399 doi: 10.1002/adma.201504572
[28]
Wu J X, Liu Y J, Tan Z J, et al. Chemical patterning of high-mobility semiconducting 2D Bi2O2Se crystals for integrated optoelectronic devices. Adv Mater, 2017, 29(44), 1704060 doi: 10.1002/adma.201704060
[29]
Li L, Guo Y C, Sun Y P, et al. A general method for the chemical synthesis of large-scale, seamless transition metal dichalcogenide electronics. Adv Mater, 2018, 30(12), 1706215 doi: 10.1002/adma.201706215
[30]
Huan Y H, Shi J P, Zou X L, et al. Vertical 1T-TaS2 synthesis on nanoporous gold for high-performance electrocatalytic applications. Adv Mater, 2018, 30(15), 1705916 doi: 10.1002/adma.201705916
[31]
Zhang T, Fu L. Controllable chemical vapor deposition growth of two-dimensional heterostructures. Chem, 2018, 4(4), 671 doi: 10.1016/j.chempr.2017.12.006
[32]
Xu R J, Jang H, Lee M H, et al. Vertical MoS2 double-layer memristor with electrochemical metallization as an atomic-scale synapse with switching thresholds approaching 100 mV. Nano Lett, 2019, 19(4), 2411 doi: 10.1021/acs.nanolett.8b05140
[33]
Zhu Y B, Li Y J, Arefe R A, et al. Monolayer molybdenum disulfide transistors with single-atomthick gates. Nano Lett, 2018, 18(6), 3807 doi: 10.1021/acs.nanolett.8b01091
[34]
Kim S, Yao Z P, Lim J M, et al. Atomic-scale observation of electrochemically reversible phase transformations in SnSe2 single crystals. Adv Mater, 2018, 30(51), 1804925 doi: 10.1002/adma.201804925
[35]
Liu C S, Yan X, Song X F, et al. A semi-floating gate memory based on van der Waals heterostructures for quasi-non-volatile applications. Nat Nano, 2018, 13, 404 doi: 10.1038/s41565-018-0102-6
[36]
Gao A Y, Lai J W, Wang Y J, et al. Observation of ballistic avalanche phenomena in nanoscale vertical InSe/BP heterostructures. Nat Nano, 2019, 14, 217 doi: 10.1038/s41565-018-0348-z
[37]
Das S, Robinson J A, Dubey M, et al. Beyond graphene: progress in novel two dimensional materials and van der Waals solids. Annu Rev Mater Res, 2015, 45, 1 doi: 10.1146/annurev-matsci-070214-021034
[38]
Sangwan V K, Beck M E, Henning A, et al. Self-aligned van der Waals heterojunction diodes and transistors. Nano Lett, 2018, 18(2), 1421 doi: 10.1021/acs.nanolett.7b05177
[39]
Lembke D, Kis A. Breakdown of high-performance monolayer MoS2 transistors. ACS Nano, 2012, 6(11), 10070 doi: 10.1021/nn303772b
[40]
Manzeli S, Ovchinnikov D, Pasquier D, et al. 2D transition metal dichalcogenides. Nat Rev Mater, 2017, 2, 17033 doi: 10.1038/natrevmats.2017.33
[41]
Luo W, Zhu M J, Peng G, et al. Carrier modulation of ambipolar few-layer MoTe2 transistors by MgO surface charge transfer doping. Adv Mater, 2018, 28(15), 1704539 doi: 10.1002/adfm.201704539
[42]
Avsar A, Marinov K, Marin E G, et al. Reconfgurable diodes based on vertical WSe2 transistors with van der Waals bonded contacts. Adv Mater, 2018, 30(18), 17072000 doi: 10.1002/adma.201707200
[43]
Kim S, Maassen J, Lee J, et al. Interstitial Mo-assisted photovoltaic effect in multilayer MoSe2 phototransistors. Adv Mater, 2018, 30(12), 1705542 doi: 10.1002/adma.201705542
[44]
Song S H, Joo M K, Neumann M, et al. Probing defect dynamics in monolayer MoS2 via noise nanospectroscopy. Nat Commun, 2017, 8, 2121 doi: 10.1038/s41467-017-02297-3
[45]
Tian H, Guo Q S, Xie Y J, et al. Anisotropic black phosphorus synaptic device for neuromorphic applications. Adv Mater, 2016, 28(25), 4991 doi: 10.1002/adma.201600166
[46]
Jena D, Banerjee K, Xing G H, et al. 2D crystal semiconductors: Intimate contacts. Nat Mater, 2014, 13, 2640 doi: 10.1038/nmat4121
[47]
Xu L P, Zhang P, Jiang H N, et al. Large-scale growth and field-effect transistors electrical engineering of atomic-layer SnS2. Small, 2019, 15(46), 1904116 doi: 10.1002/smll.201904116
[48]
Han G H, Duong D L, Keum D H, et al. Van der Waals metallic transition metal dichalcogenides. Chem Rev, 2018, 118(13), 6297 doi: 10.1021/acs.chemrev.7b00618
[49]
Schulman D S, Arnold A J, Das S. Contact engineering for 2D materials and devices. Chem Soc Rev, 2018, 47(9), 3037 doi: 10.1039/C7CS00828G
[50]
Baranowski M, Surrente A, Klopotowski L, et al. Probing the interlayer exciton physics in a MoS2/MoSe2/MoS2 van der Waals heterostructure. Nano Lett, 2017, 17(10), 6360 doi: 10.1021/acs.nanolett.7b03184
[51]
Islam M A, Kim J H, Schropp A, et al. Centimeter-scale 2D van der Waals vertical heterostructures integrated on deformable substrates enabled by gold sacrificial layer-assisted growth. Nano Lett, 2017, 17(10), 6157 doi: 10.1021/acs.nanolett.7b02776
[52]
Yan C Y, Gong C H, Wang P H, et al. 2D group IVB transition metal dichalcogenides. Adv Funct Mater, 2018, 28(39), 1803305 doi: 10.1002/adfm.201803305
[53]
Voiry D, Mohite A, Chhowalla M. Phase engineering of transition metal dichalcogenides. Chem Soc Rev, 2015, 44, 2702 doi: 10.1039/C5CS00151J
[54]
Wang X S, Song Z G, Wen W, et al. Potential 2D materials with phase transitions: structure, synthesis, and device applications. Adv Mater, 2019, 31(45), 1804682 doi: 10.1002/adma.201804682
[55]
Stark M S, Kuntz K L, Martens S J, et al. Intercalation of layered materials from bulk to 2D. Adv Mater, 2019, 31(27), 1808213 doi: 10.1002/adma.201808213
[56]
Li H, Ruan S C, Zeng Y J. Intrinsic van der Waals magnetic materials from bulk to the 2D limit: new frontiers of spintronics. Adv Mater, 2019, 31(27), 1900065 doi: 10.1002/adma.201900065
[57]
Allain A, Kang J H, Banerjee K, et al. Electrical contacts to two-dimensional semiconductors. Nat Mater, 2015, 14, 1195 doi: 10.1038/nmat4452
[58]
Kang J, Liu W, Sarkar D. Computational study of metal contacts to monolayer transition­metal dichalcogenide semiconductors. Phys Rev X, 2014, 4(3), 031005 doi: 10.1103/PhysRevX.4.031005
[59]
Ranuárez J C, Deen M J, Chen C H. A review of gate tunneling current in MOS devices. Microelectron Reliab, 2016, 46(12), 1939 doi: 10.1016/j.microrel.2005.12.006
[60]
Liu Y, Guo J, Zhu E B, et al. Approaching the Schottky–Mott limit in van der Waals metal–semiconductor junctions. Nature, 2018, 557, 696 doi: 10.1038/s41586-018-0129-8
[61]
English C D, Shine G, Dorgan V E, et al. Improved contacts to MoS2 transistors by ultra-high vacuum metal deposition. Nano Lett, 2016, 16(6), 3824 doi: 10.1021/acs.nanolett.6b01309
[62]
Stokbro K, Engelund M, Blom A. Atomic­scale model for the contact resistance of the nickel­graphene interface. Phys Rev B, 2012, 85(16), 165442 doi: 10.1103/PhysRevB.85.165442
[63]
Popov I, Seifert G, Tománek D. Designing electrical contacts to MoS2 monolayers: a computational study. Phys Rev Lett, 2012, 108(15), 156802 doi: 10.1103/PhysRevLett.108.156802
[64]
Liu W, Kang J H, Cao W, et al. High­ performance few­ layer­ MoS2 field-effect-transistor with record low contact­resistance. IEEE Int Electron Devices Meet, 2013, 19.4. 1 doi: 10.1109/IEDM.2013.6724660
[65]
Wang L, Meric I, Huang P Y, et al. One-dimensional electrical contact to a two-dimensional material. Science, 2013, 342(6158), 614 doi: 10.1126/science.1244358
[66]
Cui X, Lee G H, Kim Y D, et al. Multi-terminal transport measurements of MoS2 using a van der Waals heterostructure device platform. Nat Mater, 2015, 10, 534 doi: 10.1038/nnano.2015.70
[67]
Chai Y, Ionescu R, Su S S, et al. Making one-dimensional electrical contacts to molybdenum disulfid-based heterostructures through plasma etching. Phys Status Solidi A, 2016, 213(5), 1358 doi: 10.1002/pssa.201532799
[68]
Matsuda Y, Deng W Q, Goddard W A. Contact resistance for “end-contacted” metal−graphene and metal−nanotube interfaces from quantum mechanics. J Phys Chem C, 2010, 114(41), 17845 doi: 10.1021/jp806437y
[69]
Karpiak B, Dankert A, Cummings A W, et al. 1D ferromagnetic edge contacts to 2D graphene/h-BN heterostructures. 2D Mater, 2017, 5(1), 014001 doi: 10.1088/2053-1583/aa8d2b
[70]
Zhang Y, Yin L, Chu J W, et al. Edge-epitaxial growth of 2D NbS2-WS2 lateral metal-semiconductor heterostructures. Adv Mater, 2018, 30(40), 1803665 doi: 10.1002/adma.201803665
[71]
Gong Y J, Lei S D, Ye G L, et al. Two-step growth of two-dimensional WSe2/MoSe2 heterostructures. Nano Lett, 2015, 15(9), 6135 doi: 10.1021/acs.nanolett.5b02423
[72]
Gong Y G, Lin Z, Ye G L, et al. Tellurium-assisted low-temperature synthesis of MoS2 and WS2 monolayers. ACS Nano, 2015, 9(12), 11658 doi: 10.1021/acsnano.5b05594
[73]
Ji Q Q, Li C, Wang J L, et al. Metallic vanadium disulfide nanosheets as a platform material for multifunctional electrode applications. Nano Lett, 2017, 17(8), 4908 doi: 10.1021/acs.nanolett.7b01914
[74]
Zhou J D, Lin J H, Huang X W, et al. A library of atomically thin metal chalcogenides. Nature, 2018, 556, 358 doi: 10.1038/s41586-018-0008-3
[75]
Leong W S, Ji Q Q, Mao N N, et al. Synthetic lateral metal–semiconductor heterostructures of transition metal disulfides. J Am Chem Soc, 2018, 140(39), 12354 doi: 10.1021/jacs.8b07806
[76]
Lee C S, Oh S J, Heo H, et al. Epitaxial van der Waals contacts between transition-metal dichalcogenide monolayer polymorphs. Nano Lett, 2019, 19(3), 1814 doi: 10.1021/acs.nanolett.8b04869
[77]
Wu R X, Tao Q Y, Dang W Q, et al. van der Waals epitaxial growth of atomically thin 2D metals on dangling-bond-free WSe2 and WS2. Adv Funct Mater, 2019, 29(12), 1806611 doi: 10.1002/adfm.201806611
[78]
Jin Y Y, Zeng Z Y, Xu Z W, et al. Synthesis and transport properties of degenerate p-type Nb-doped WS2 monolayers. Chem Mater, 2019, 31(9), 3534 doi: 10.1021/acs.chemmater.9b00913
[79]
Suh J, Park T E, Lin D Y, et al. Doping against the native propensity of MoS2: degenerate hole doping by cation substitution. Nano Lett, 2014, 14(12), 6976 doi: 10.1021/nl503251h
[80]
Kappera R, Voiry D, Yalcin S E, et al. Phase-engineered low-resistance contacts for ultrathin MoS2 transistors. Nat Mater, 2014, 13, 1128 doi: 10.1038/nmat4080
[81]
Zhu J Q, Wang Z G, Yu H, et al. Argon plasma induced phase transition in monolayer MoS2. J Am Chem Soc, 2017, 139(30), 10216 doi: 10.1021/jacs.7b05765
[82]
Gong Y J, Yuan H T, Wu C L, et al. Spatially controlled doping of two-dimensional SnS2 through intercalation for electronics. Nat Nano, 2018, 13, 294 doi: 10.1038/s41565-018-0069-3
[83]
Schottky W. Zur Halbleitertheorie der sperrschicht-und spitzengleichrichter. Z Phys A, 1939, 113, 367 doi: 10.1007/BF01340116
[84]
Mott N. The theory of crystal rectifers. Proc R Soc Lond A, 1939, 171, 27 doi: 10.1098/rspa.1939.0051
[85]
Bardeen J. Surface states and rectifcation at a metal semi-conductor contact. Phys Rev, 1947, 71, 717 doi: 10.1103/PhysRev.71.717
[86]
Das S, Chen H Y, Penumatcha A V, et al. High performance multi-layer MoS2 transistors with scandium contacts. Nano Lett, 2013, 13(1), 100 doi: 10.1021/nl303583v
[87]
Wang Y, Kim J C, Wu R J, et al. Van der Waals contacts between three-dimensional metals and two-dimensional semiconductors. Nature, 2019, 568, 70 doi: 10.1038/s41586-019-1052-3
[88]
Kang J, Sarkar D, Liu W, et al. A computational study of metal­contacts to beyond­graphene 2D semiconductor materials. IEEE Int Electron Devices Meet, 2012, 407
[89]
Khatami Y, Li H, Xu C, et al. Metal­-to-­multilayer-­graphene contact—Part II: analysis of contact resistance. IEEE Trans Electron Devices, 2012, 59, 2453 doi: 10.1109/TED.2012.2205257
[90]
Khatami Y, Li H, Xu C, et al. Metal­-to-­multilayer-­graphene contact—Part I: contact resistance modeling. IEEE Trans Electron Devices, 2012, 59, 2444 doi: 10.1109/TED.2012.2205256
[91]
Zhao M, Ye Y, Han Y, et al. Large-scale chemical assembly of atomically thin transistors and circuits. Nat Nano, 2016, 11, 954 doi: 10.1038/nnano.2016.115
[92]
Hong W, Shim G W, Yang S Y, et al. Improved electrical contact properties of MoS2-graphene lateral heterostructure. Adv Funct Mater, 2019, 29(6), 1807550 doi: 10.1002/adfm.201807550
[93]
Leong W S, Nai C T, Tong J T L. What does annealing do to metal-graphene contacts. Nano Lett, 2014, 14(7), 3840 doi: 10.1021/nl500999r
[94]
Léonard F, Talin A A. Electrical contacts to one- and two-dimensional nanomaterials. Nat Nano, 2011, 6, 773 doi: 10.1038/nnano.2011.196
[95]
Heine V. Theory of surface states. Phys Rev, 1965, 138, A1689 doi: 10.1103/PhysRev.138.A1689
[96]
Liu L N, Wu J X, Wu L Y, et al. Phase-selective synthesis of 1T’ MoS2 monolayers and heterophase bilayers. Nat Mater, 2018, 17, 1108 doi: 10.1038/s41563-018-0187-1
[97]
Zheng J Y, Yan X X, Lu Z X, et al. High-mobility multilayered MoS2 flakes with low contact resistance grown by chemical vapor deposition. Adv Mater, 2017, 29(13), 1604540 doi: 10.1002/adma.201604540
[98]
Gong C, Colombo L, Wallace R M, et al. The unusual mechanism of partial fermi level pinning at metal –MoS2 interfaces. Nano Lett, 2014, 14(4), 1714 doi: 10.1021/nl403465v
[99]
Saidi W A. Trends in the adsorption and growth morphology of metals on the MoS2 (001) surface. Cryst Growth Des, 2015, 15(7), 3190 doi: 10.1021/acs.cgd.5b00269
[100]
Meng L J, Ma Y, Si K P, et al. Recent advances of phase engineering in group VI transition metal dichalcogenides. Tungsten, 2019, 1, 46 doi: 10.1007/s42864-019-00012-x
[101]
Li J, Yang X D, Liu Y, et al. General synthesis of two-dimensional van der Waals heterostructure arrays. Nature, 2020, 579, 368 doi: 10.1038/s41586-020-2098-y
Fig. 1.  (Color online) Atomic structure of representative 2D semiconductor materials and phase engineered contacts. (a, b) Top and side view of 2H stacked structure of 2D semiconductor. (c) Device model of 2D SCs based device. (d–f) Different types of metal–semiconductor junction with contact interface.

Fig. 2.  (Color online) (a, b) 3D top contact and 3D edge contact configuration of metal-2D SCs contact. (c, d) 2D top contact and 2D edge contact of metallic 2D-SCs contact geometries.

Fig. 3.  (Color online) Schematic diagram of a conventional Si-based NMOS FET.

Fig. 4.  (Color online) (a) Schematic diagram of various metal–MoS2 band alignments along with work function of metal (ФM). The Fermi level of metal is lined up close to conduction band of MoS2. The left-hand part in Fig. 4(a) is the actual ФSB extracted from experiment, which is different from the theoretical value calculated by the difference of ФM (right-hand part in Fig. 4(a)) and electron affinity (χ) of MoS2. For example, theoretical values of ФSB for Sc–MoS2 and Pt–MoS2 contact are about –0.7 and 1.4 eV, respectively. However, the actual ФSB obtained from experiment is only 30 and 230 meV, indicating that there is a strong Fermi level pinning effect at the interface of metal and 2D SCs. (b) Energy band diagrams of MoS2 with and without 2D metallic materials.

Fig. 5.  (Color online) Metal contact investigation of MoS2 device. (a) Schematic diagram of back gated MoS2 transistor. (b, c) SEM and AFM images of device with MoS2 thickness of 3 nm. (d) The expected position of the metal Fermi level across the band of MoS2, where the ФSB was decided by the Schottky–Mott rule. (e) Transfer characteristics of MoS2 device with different contact metal. The inset is the actual position of Fermi level of from experimental date. (f) Temperature-dependent transfer curves with Ni contact, where the contribution of thermionic emission and thermally assisted tunneling are marked. (g) Arrhenius-type plot from (a). (h) Extracted actual ФSB for Ni-contacted MoS2 device. (i) The relationship of ФSB with metal work function[86]. Copyright 2013, American Chemical Society.

Fig. 6.  (Color online) In contacted MoS2 transistors. (a) Device mode of MoS2 based back-gated device. The electrodes consist of 10 nm In layer capped with 100 nm Au. (b) Cross-sectional annular dark field (ADF) scanning transmission electron microscopy (STEM) of interface of In-MoS2. (c, d) Extracted contact resistance using transmission line method for MoS2 with thickness of 0.7 and 8.1 nm, respectively. (e, f) Comparison of contact resistance versus carrier concentration with different contact materials from literatures. (g, h) Transfer characteristics of device with monolayer MoS2 and temperature-dependent transfer curves for 8 nm MoS2 device. (i) Output curves with linear relationship indicates ohmic contact. (j) Extracted ФSB with value of 110 meV, indicates the ideal contact between the interface of In and MoS2, which is nearly the same as the value decided by the Schottky–Mott rule. The inset is the energy band diagram of MoS2 and In[87]. Copyright 2019, Nature Publishing Group.

Fig. 7.  (Color online) Transferred metal electrode contacted MoS2 FET. (a–c) Cross-sectional atomic mode and optical images of MoS2 device with transferred Au and the transferred Au mechanically released. (d–f) Cross-sectional schematics and optical images of MoS2 device with traditional electron-beam-deposited Au and the deposited Au mechanically released. (g, h) Cross-sectional schematics and TEM images of transferred and evaporated Au. (i, j) Transfer curves of MoS2 devices with different transferred and deposited metals. (k) Experimentally extracted ФSB for different transferred and evaporated metals[60]. Copyright 2018, Nature Publishing Group.

Fig. 8.  (Color online) Edge contact investigation of MoS2 device. (a) Schematic diagram of hBN encapsulated MoS2 device with graphene edge contact. (b–d) Temperature dependent output curves, contact resistance and temperature dependent Hall mobility, respectively[66]. Copyright 2016, Nature Publishing Group (e) Schematic of Al2O3 capped edge contacted MoS2 device. (f–h) Output curves, transfer characteristic and mobility with different drain voltage for Al2O3 capped MoS2 device. (i) Schematic of h-BN capped edge contacted MoS2 device. (j–l) Output curves, transfer characteristic and mobility with different drain voltage for hBN capped MoS2 device[67]. Copyright 2016, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fig. 9.  (Color online) Contact engineering of vertical 2D metallic-2H WSe2 heterostructure. (a) Sequential growth scheme of vertical WSe2 and WT2 heterostructure. The inset is the optical images of WSe2 and WTe2. (b) Device mode of WSe2 with and without contact. (c, d) Output curves and temperature-dependent conductivity of WSe2 device with WTe2 and Ti contact. (e) Built-in potential energy versus back-gated voltage for Ti and WTe2 contacted WSe2 devices. (f) ФSB height with the function of metal work function[76]. Copyright 2013, American Chemical Society. (g, h) Atomic structure of van der Waals epitaxy growth of 2D metallic-SCs heterostructure and optical image of NbTe2-WSe2 heterostructure. (i, j) Schematic model of WSe2 device with NbTe2 and Ti contact. (k–n) Current–voltage and transfer characteristics of WSe2 device with and without NbTe2 contact. The inset is optical images of fabricated devices[77]. Copyright 2019, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fig. 10.  (Color online) Contact engineering of lateral graphene–MoS2 and VS2–MoS2 heterostructures. (a) Schematic diagram of MoS2–graphene lateral heterostructure. (b, c) Transfer and output curves of graphene contacted MoS2 device. (d) Statistics of obtained mobility from graphene contacted MoS2 device[91]. Copyright 2016, Nature Publishing Group. (e) Schematic fabrication of the MoS2–graphene lateral heterostructure. (f, g) Representative transfer and output curves of graphene contacted MoS2 deice. (h) Total, contact and channel resistance of graphene contacted MoS2 device[92]. Copyright 2016, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. (i) Device schematic of VS2 contacted MoS2. (j) IdsVds curves of MoS2 device with VS2 and Ni contact. (k) Extracted ФSB of VS2 and Ni contacted MoS2 as a function of Vbg. (l) Contact resistance of Ni and VS2 contacted MoS2 devices[75]. Copyright 2018, American Chemical Society.

Fig. 11.  (Color online) Electron donation, laser or Ar plasma induced metallic phase as contact. (a) Electrostatic force microscopy phase image of 1T–2H–1T lateral MoS2 heterostructure. (b–d) Resistance, output and transfer curves of 2H phase MoS2 with metallic 1T phase MoS2 contact. The inset is the device model of MoS2 device with Au and 1T metallic MoS2 contact[80]. Copyright 2014, Nature Publishing Group. Laser induced phase transition of metallic 1T’-MoTe2. (e) Atomic structure and laser treated process. (f) Device schematic with metallic 1T’-MoTe2 contact. (g) Output characteristic of MoTe2 device with 1T’-MoTe2 contact. (h) Field-effect mobility as a function of temperature of MoTe2 device with Au and metallic MoTe2 contact2 contact[80]. Copyright 2015, American Association for the Advancement of Science (AAAS). (i) Atomic structure and schematic representation of plasma-treated process. (j) Device models with Au or 1T/2H phase MoS2 contact. (k, l) Output and transfer curves with different Au and 1T/2H phase MoS2 contact[81]. Copyright 2017, American Chemical Society.

Fig. 12.  (Color online) Intercalation induced phase transition of SnS2. (a) and (b) Atomic structures of pristine SnS2, Cu and Co intercalated SnS2. (c–f) Optical images of pure SnS2, Cu, Co and Cu–Co intercalated SnS2. (g) Temperature-dependent resistance of SnS2, Cu–SnS2, Co–SnS2 and few layer graphene, where the Cu–SnS2 presents semiconductor behavior while the Co–SnS2 behaves as a metal like graphene. (h) Transfer curves of Cu–SnS2 with p-type characteristic. (i) IV curves of Co–SnS2 contacted SnS2 and Cu–SnS2 devices. (j) SnS2/Cu–SnS2 junction with and without metallic Co–SnS2 contact[82]. Copyright 2018, Nature Publishing Group.

Fig. 13.  (Color online) General scalable synthesis of precisely controlled nucleation position and growth process of 2D metallic-SCs heterostructures. (a) Schematic process of selectively patterned periodic defect arrays of 2D SCs (MoS2, WSe2 and WS2) to grow 2D metallic materials (VSe2, VS2, CoTe2, NiTe2 and NbTe2). (b) Schematic diagram of VSe2 growth on patterned sites of WSe2. (c–e) Optical images of periodical arrays of 2D metallic materials on WSe2. (f) Optical image of VSe2 contacted WSe2 FET periodical arrays. (g–j) Electrical characterizations of the VSe2 contacted WSe2 FET[101]. Copyright 2020, Nature Publishing Group.

[1]
Schaller R. Moore's law: past, present and future. IEEE Spectrum, 1997, 34(6), 52 doi: 10.1109/6.591665
[2]
Frank D J, Dennard R H, Nowak E, et al. Device scaling limits of Si MOSFETs and their application dependencies. Proc IEEE, 2001, 89(3), 259 doi: 10.1109/5.915374
[3]
Sarkar D, Xie X J, Liu W, et al. A subthermionic tunnel field-effect transistor with an atomically thin channel. Nature, 2015, 526, 91 doi: 10.1038/nature15387
[4]
Arnold A J, Razavieh A, Nas J R, et al. Mimicking neurotransmitter release in chemical synapses via hysteresis engineering in MoS2 transistors. ACS Nano, 2017, 11(3), 3110 doi: 10.1021/acsnano.7b00113
[5]
Gong Y J, Shi G, Zhang Z H, et al. Direct chemical conversion of graphene to boronand nitrogen-and carbon-containing atomic layers. Nat Common, 2014, 5, 3193 doi: 10.1038/ncomms4193
[6]
Xie Y L, Lian B, Jäck B, et al. Spectroscopic signatures of many-body correlations in magic-angle twisted bilayer graphene. Nature, 2019, 572, 101 doi: 10.1038/s41586-019-1422-x
[7]
Li L F, Liu W, Gao A Y, et al. Plasmon excited ultrahot carriers and negative differential photoresponse in a vertical graphene van der Waals heterostructure. Nano Lett, 2019, 19(5), 3295 doi: 10.1021/acs.nanolett.9b00908
[8]
Novoselov K S, Geim A K, Morozov S V, et al. Two-dimensional gas of massless Dirac fermions in graphene. Nature, 2005, 438, 197 doi: 10.1038/nature04233
[9]
Zhang Y B, Tan Y W, Stormer H L, et al. Experimental observation of the quantum Hall effect and Berry's phase in graphene. Nature, 2005, 438, 201 doi: 10.1038/nature04235
[10]
Lee C, Wei X D, Kysar J W, et al. Measurement of the elastic properties and intrinsic strength of monolayer graphene. Science, 2008, 321(5887), 385 doi: 10.1126/science.1157996
[11]
Liu Y P, Yudhistira I, Yang M, et al. Phonon-mediated colossal magnetoresistance in graphene/black phosphorus heterostructures. Nano Lett, 2018, 18(6), 3377 doi: 10.1021/acs.nanolett.8b00155
[12]
Huang S Y, Zhang G W, Fan F R, et al. Strain-tunable van der Waals interactions in few-layer black phosphorus. Nat Common, 2019, 10, 2447 doi: 10.1038/s41467-019-10483-8
[13]
Chaudhary K, Tamagnone M, Rezaee M, et al. Engineering phonon polaritons in van der Waals heterostructures to enhance in-plane optical anisotropy. Sci Adv, 2019, 5(4), eaau7171 doi: 10.1126/sciadv.aau7171
[14]
Kim J M, Baik S S, Ryu S H, et al. Observation of tunable band gap and anisotropic Dirac semimetal state in black phosphorus. Science, 2015, 349(6249), 723 doi: 10.1126/science.aaa6486
[15]
Peng R M, Khaliji K, Youngblood N, et al. Midinfrared electro-optic modulation in few-layer black phosphorus. Nano Lett, 2017, 17(10), 6315 doi: 10.1021/acs.nanolett.7b03050
[16]
Liu Z, Gong Y G, Zhou W, et al. Ultrathin high-temperature oxidation-resistant coatings of hexagonal boron nitride. Nat Commun, 2013, 4, 2541 doi: 10.1038/ncomms3541
[17]
Wu E X, Xie Y, Zhang J, et al. Dynamically controllable polarity modulation of MoTe2 field-effect transistors through ultraviolet light and electrostatic activation. Sci Adv, 2019, 5(5), eaav3430 doi: 10.1126/sciadv.aav3430
[18]
Park H J, Tay R Y J, Wang X, et al. Double-spiral hexagonal boron nitride and shear strained coalescence boundary. Nano Lett, 2019, 19(7), 4229 doi: 10.1021/acs.nanolett.8b05034
[19]
Song L, Ci L J, Lu H, et al. Large scale growth and characterization of atomic hexagonal boron nitride layers. Nano Lett, 2010, 10(8), 3209 doi: 10.1021/nl1022139
[20]
Ci L J, Song L, Jin C J, et al. Atomic layers of hybridized boron nitride and graphene domains. Nat Mater, 2010, 9, 430 doi: 10.1038/nmat2711
[21]
Gong Y G, Lin J H, Wang X L, et al. Vertical and in-plane heterostructures from WS2/MoS2 monolayers. Nat Mater, 2014, 13, 1135 doi: 10.1038/nmat4091
[22]
Gong Y G, Liu Z, Lupini A R, et al. Band gap engineering and layer-by-layer mapping of selenium doped molybdenum disulfide. Nano Lett, 2014, 14(2), 442 doi: 10.1021/nl4032296
[23]
Ma Y, Ajayan P M, Gong Y J, et al. Recent advances in synthesis and applications of 2D junctions. Small, 2018, 14(38), 1801606 doi: 10.1002/smll.201801606
[24]
Lin Y C, Li S S, Komsa H P, et al. Revealing the atomic defects of WS2 governing its distinct optical emissions. Adv Funct Mater, 2017, 28(4), 1704210 doi: 10.1002/adfm.201704210
[25]
Sun L F, Leong W S, Yang S Z, et al. Concurrent synthesis of high-performance monolayer transition metal disulfdes. Adv Funct Mater, 2017, 27(15), 1605896 doi: 10.1002/adfm.201605896
[26]
Zhou Y, Jang H J, Woods J M, et al. Direct synthesis of large-scale WTe2 thin films with low thermal conductivity. Adv Funct Mater, 2017, 27(8), 1605928 doi: 10.1002/adfm.201605928
[27]
Zhao Y D, Qiao J S, Yu P, et al. Extraordinarily strong interlayer interaction in 2D layered PtS2. Adv Mater, 2017, 28(12), 2399 doi: 10.1002/adma.201504572
[28]
Wu J X, Liu Y J, Tan Z J, et al. Chemical patterning of high-mobility semiconducting 2D Bi2O2Se crystals for integrated optoelectronic devices. Adv Mater, 2017, 29(44), 1704060 doi: 10.1002/adma.201704060
[29]
Li L, Guo Y C, Sun Y P, et al. A general method for the chemical synthesis of large-scale, seamless transition metal dichalcogenide electronics. Adv Mater, 2018, 30(12), 1706215 doi: 10.1002/adma.201706215
[30]
Huan Y H, Shi J P, Zou X L, et al. Vertical 1T-TaS2 synthesis on nanoporous gold for high-performance electrocatalytic applications. Adv Mater, 2018, 30(15), 1705916 doi: 10.1002/adma.201705916
[31]
Zhang T, Fu L. Controllable chemical vapor deposition growth of two-dimensional heterostructures. Chem, 2018, 4(4), 671 doi: 10.1016/j.chempr.2017.12.006
[32]
Xu R J, Jang H, Lee M H, et al. Vertical MoS2 double-layer memristor with electrochemical metallization as an atomic-scale synapse with switching thresholds approaching 100 mV. Nano Lett, 2019, 19(4), 2411 doi: 10.1021/acs.nanolett.8b05140
[33]
Zhu Y B, Li Y J, Arefe R A, et al. Monolayer molybdenum disulfide transistors with single-atomthick gates. Nano Lett, 2018, 18(6), 3807 doi: 10.1021/acs.nanolett.8b01091
[34]
Kim S, Yao Z P, Lim J M, et al. Atomic-scale observation of electrochemically reversible phase transformations in SnSe2 single crystals. Adv Mater, 2018, 30(51), 1804925 doi: 10.1002/adma.201804925
[35]
Liu C S, Yan X, Song X F, et al. A semi-floating gate memory based on van der Waals heterostructures for quasi-non-volatile applications. Nat Nano, 2018, 13, 404 doi: 10.1038/s41565-018-0102-6
[36]
Gao A Y, Lai J W, Wang Y J, et al. Observation of ballistic avalanche phenomena in nanoscale vertical InSe/BP heterostructures. Nat Nano, 2019, 14, 217 doi: 10.1038/s41565-018-0348-z
[37]
Das S, Robinson J A, Dubey M, et al. Beyond graphene: progress in novel two dimensional materials and van der Waals solids. Annu Rev Mater Res, 2015, 45, 1 doi: 10.1146/annurev-matsci-070214-021034
[38]
Sangwan V K, Beck M E, Henning A, et al. Self-aligned van der Waals heterojunction diodes and transistors. Nano Lett, 2018, 18(2), 1421 doi: 10.1021/acs.nanolett.7b05177
[39]
Lembke D, Kis A. Breakdown of high-performance monolayer MoS2 transistors. ACS Nano, 2012, 6(11), 10070 doi: 10.1021/nn303772b
[40]
Manzeli S, Ovchinnikov D, Pasquier D, et al. 2D transition metal dichalcogenides. Nat Rev Mater, 2017, 2, 17033 doi: 10.1038/natrevmats.2017.33
[41]
Luo W, Zhu M J, Peng G, et al. Carrier modulation of ambipolar few-layer MoTe2 transistors by MgO surface charge transfer doping. Adv Mater, 2018, 28(15), 1704539 doi: 10.1002/adfm.201704539
[42]
Avsar A, Marinov K, Marin E G, et al. Reconfgurable diodes based on vertical WSe2 transistors with van der Waals bonded contacts. Adv Mater, 2018, 30(18), 17072000 doi: 10.1002/adma.201707200
[43]
Kim S, Maassen J, Lee J, et al. Interstitial Mo-assisted photovoltaic effect in multilayer MoSe2 phototransistors. Adv Mater, 2018, 30(12), 1705542 doi: 10.1002/adma.201705542
[44]
Song S H, Joo M K, Neumann M, et al. Probing defect dynamics in monolayer MoS2 via noise nanospectroscopy. Nat Commun, 2017, 8, 2121 doi: 10.1038/s41467-017-02297-3
[45]
Tian H, Guo Q S, Xie Y J, et al. Anisotropic black phosphorus synaptic device for neuromorphic applications. Adv Mater, 2016, 28(25), 4991 doi: 10.1002/adma.201600166
[46]
Jena D, Banerjee K, Xing G H, et al. 2D crystal semiconductors: Intimate contacts. Nat Mater, 2014, 13, 2640 doi: 10.1038/nmat4121
[47]
Xu L P, Zhang P, Jiang H N, et al. Large-scale growth and field-effect transistors electrical engineering of atomic-layer SnS2. Small, 2019, 15(46), 1904116 doi: 10.1002/smll.201904116
[48]
Han G H, Duong D L, Keum D H, et al. Van der Waals metallic transition metal dichalcogenides. Chem Rev, 2018, 118(13), 6297 doi: 10.1021/acs.chemrev.7b00618
[49]
Schulman D S, Arnold A J, Das S. Contact engineering for 2D materials and devices. Chem Soc Rev, 2018, 47(9), 3037 doi: 10.1039/C7CS00828G
[50]
Baranowski M, Surrente A, Klopotowski L, et al. Probing the interlayer exciton physics in a MoS2/MoSe2/MoS2 van der Waals heterostructure. Nano Lett, 2017, 17(10), 6360 doi: 10.1021/acs.nanolett.7b03184
[51]
Islam M A, Kim J H, Schropp A, et al. Centimeter-scale 2D van der Waals vertical heterostructures integrated on deformable substrates enabled by gold sacrificial layer-assisted growth. Nano Lett, 2017, 17(10), 6157 doi: 10.1021/acs.nanolett.7b02776
[52]
Yan C Y, Gong C H, Wang P H, et al. 2D group IVB transition metal dichalcogenides. Adv Funct Mater, 2018, 28(39), 1803305 doi: 10.1002/adfm.201803305
[53]
Voiry D, Mohite A, Chhowalla M. Phase engineering of transition metal dichalcogenides. Chem Soc Rev, 2015, 44, 2702 doi: 10.1039/C5CS00151J
[54]
Wang X S, Song Z G, Wen W, et al. Potential 2D materials with phase transitions: structure, synthesis, and device applications. Adv Mater, 2019, 31(45), 1804682 doi: 10.1002/adma.201804682
[55]
Stark M S, Kuntz K L, Martens S J, et al. Intercalation of layered materials from bulk to 2D. Adv Mater, 2019, 31(27), 1808213 doi: 10.1002/adma.201808213
[56]
Li H, Ruan S C, Zeng Y J. Intrinsic van der Waals magnetic materials from bulk to the 2D limit: new frontiers of spintronics. Adv Mater, 2019, 31(27), 1900065 doi: 10.1002/adma.201900065
[57]
Allain A, Kang J H, Banerjee K, et al. Electrical contacts to two-dimensional semiconductors. Nat Mater, 2015, 14, 1195 doi: 10.1038/nmat4452
[58]
Kang J, Liu W, Sarkar D. Computational study of metal contacts to monolayer transition­metal dichalcogenide semiconductors. Phys Rev X, 2014, 4(3), 031005 doi: 10.1103/PhysRevX.4.031005
[59]
Ranuárez J C, Deen M J, Chen C H. A review of gate tunneling current in MOS devices. Microelectron Reliab, 2016, 46(12), 1939 doi: 10.1016/j.microrel.2005.12.006
[60]
Liu Y, Guo J, Zhu E B, et al. Approaching the Schottky–Mott limit in van der Waals metal–semiconductor junctions. Nature, 2018, 557, 696 doi: 10.1038/s41586-018-0129-8
[61]
English C D, Shine G, Dorgan V E, et al. Improved contacts to MoS2 transistors by ultra-high vacuum metal deposition. Nano Lett, 2016, 16(6), 3824 doi: 10.1021/acs.nanolett.6b01309
[62]
Stokbro K, Engelund M, Blom A. Atomic­scale model for the contact resistance of the nickel­graphene interface. Phys Rev B, 2012, 85(16), 165442 doi: 10.1103/PhysRevB.85.165442
[63]
Popov I, Seifert G, Tománek D. Designing electrical contacts to MoS2 monolayers: a computational study. Phys Rev Lett, 2012, 108(15), 156802 doi: 10.1103/PhysRevLett.108.156802
[64]
Liu W, Kang J H, Cao W, et al. High­ performance few­ layer­ MoS2 field-effect-transistor with record low contact­resistance. IEEE Int Electron Devices Meet, 2013, 19.4. 1 doi: 10.1109/IEDM.2013.6724660
[65]
Wang L, Meric I, Huang P Y, et al. One-dimensional electrical contact to a two-dimensional material. Science, 2013, 342(6158), 614 doi: 10.1126/science.1244358
[66]
Cui X, Lee G H, Kim Y D, et al. Multi-terminal transport measurements of MoS2 using a van der Waals heterostructure device platform. Nat Mater, 2015, 10, 534 doi: 10.1038/nnano.2015.70
[67]
Chai Y, Ionescu R, Su S S, et al. Making one-dimensional electrical contacts to molybdenum disulfid-based heterostructures through plasma etching. Phys Status Solidi A, 2016, 213(5), 1358 doi: 10.1002/pssa.201532799
[68]
Matsuda Y, Deng W Q, Goddard W A. Contact resistance for “end-contacted” metal−graphene and metal−nanotube interfaces from quantum mechanics. J Phys Chem C, 2010, 114(41), 17845 doi: 10.1021/jp806437y
[69]
Karpiak B, Dankert A, Cummings A W, et al. 1D ferromagnetic edge contacts to 2D graphene/h-BN heterostructures. 2D Mater, 2017, 5(1), 014001 doi: 10.1088/2053-1583/aa8d2b
[70]
Zhang Y, Yin L, Chu J W, et al. Edge-epitaxial growth of 2D NbS2-WS2 lateral metal-semiconductor heterostructures. Adv Mater, 2018, 30(40), 1803665 doi: 10.1002/adma.201803665
[71]
Gong Y J, Lei S D, Ye G L, et al. Two-step growth of two-dimensional WSe2/MoSe2 heterostructures. Nano Lett, 2015, 15(9), 6135 doi: 10.1021/acs.nanolett.5b02423
[72]
Gong Y G, Lin Z, Ye G L, et al. Tellurium-assisted low-temperature synthesis of MoS2 and WS2 monolayers. ACS Nano, 2015, 9(12), 11658 doi: 10.1021/acsnano.5b05594
[73]
Ji Q Q, Li C, Wang J L, et al. Metallic vanadium disulfide nanosheets as a platform material for multifunctional electrode applications. Nano Lett, 2017, 17(8), 4908 doi: 10.1021/acs.nanolett.7b01914
[74]
Zhou J D, Lin J H, Huang X W, et al. A library of atomically thin metal chalcogenides. Nature, 2018, 556, 358 doi: 10.1038/s41586-018-0008-3
[75]
Leong W S, Ji Q Q, Mao N N, et al. Synthetic lateral metal–semiconductor heterostructures of transition metal disulfides. J Am Chem Soc, 2018, 140(39), 12354 doi: 10.1021/jacs.8b07806
[76]
Lee C S, Oh S J, Heo H, et al. Epitaxial van der Waals contacts between transition-metal dichalcogenide monolayer polymorphs. Nano Lett, 2019, 19(3), 1814 doi: 10.1021/acs.nanolett.8b04869
[77]
Wu R X, Tao Q Y, Dang W Q, et al. van der Waals epitaxial growth of atomically thin 2D metals on dangling-bond-free WSe2 and WS2. Adv Funct Mater, 2019, 29(12), 1806611 doi: 10.1002/adfm.201806611
[78]
Jin Y Y, Zeng Z Y, Xu Z W, et al. Synthesis and transport properties of degenerate p-type Nb-doped WS2 monolayers. Chem Mater, 2019, 31(9), 3534 doi: 10.1021/acs.chemmater.9b00913
[79]
Suh J, Park T E, Lin D Y, et al. Doping against the native propensity of MoS2: degenerate hole doping by cation substitution. Nano Lett, 2014, 14(12), 6976 doi: 10.1021/nl503251h
[80]
Kappera R, Voiry D, Yalcin S E, et al. Phase-engineered low-resistance contacts for ultrathin MoS2 transistors. Nat Mater, 2014, 13, 1128 doi: 10.1038/nmat4080
[81]
Zhu J Q, Wang Z G, Yu H, et al. Argon plasma induced phase transition in monolayer MoS2. J Am Chem Soc, 2017, 139(30), 10216 doi: 10.1021/jacs.7b05765
[82]
Gong Y J, Yuan H T, Wu C L, et al. Spatially controlled doping of two-dimensional SnS2 through intercalation for electronics. Nat Nano, 2018, 13, 294 doi: 10.1038/s41565-018-0069-3
[83]
Schottky W. Zur Halbleitertheorie der sperrschicht-und spitzengleichrichter. Z Phys A, 1939, 113, 367 doi: 10.1007/BF01340116
[84]
Mott N. The theory of crystal rectifers. Proc R Soc Lond A, 1939, 171, 27 doi: 10.1098/rspa.1939.0051
[85]
Bardeen J. Surface states and rectifcation at a metal semi-conductor contact. Phys Rev, 1947, 71, 717 doi: 10.1103/PhysRev.71.717
[86]
Das S, Chen H Y, Penumatcha A V, et al. High performance multi-layer MoS2 transistors with scandium contacts. Nano Lett, 2013, 13(1), 100 doi: 10.1021/nl303583v
[87]
Wang Y, Kim J C, Wu R J, et al. Van der Waals contacts between three-dimensional metals and two-dimensional semiconductors. Nature, 2019, 568, 70 doi: 10.1038/s41586-019-1052-3
[88]
Kang J, Sarkar D, Liu W, et al. A computational study of metal­contacts to beyond­graphene 2D semiconductor materials. IEEE Int Electron Devices Meet, 2012, 407
[89]
Khatami Y, Li H, Xu C, et al. Metal­-to-­multilayer-­graphene contact—Part II: analysis of contact resistance. IEEE Trans Electron Devices, 2012, 59, 2453 doi: 10.1109/TED.2012.2205257
[90]
Khatami Y, Li H, Xu C, et al. Metal­-to-­multilayer-­graphene contact—Part I: contact resistance modeling. IEEE Trans Electron Devices, 2012, 59, 2444 doi: 10.1109/TED.2012.2205256
[91]
Zhao M, Ye Y, Han Y, et al. Large-scale chemical assembly of atomically thin transistors and circuits. Nat Nano, 2016, 11, 954 doi: 10.1038/nnano.2016.115
[92]
Hong W, Shim G W, Yang S Y, et al. Improved electrical contact properties of MoS2-graphene lateral heterostructure. Adv Funct Mater, 2019, 29(6), 1807550 doi: 10.1002/adfm.201807550
[93]
Leong W S, Nai C T, Tong J T L. What does annealing do to metal-graphene contacts. Nano Lett, 2014, 14(7), 3840 doi: 10.1021/nl500999r
[94]
Léonard F, Talin A A. Electrical contacts to one- and two-dimensional nanomaterials. Nat Nano, 2011, 6, 773 doi: 10.1038/nnano.2011.196
[95]
Heine V. Theory of surface states. Phys Rev, 1965, 138, A1689 doi: 10.1103/PhysRev.138.A1689
[96]
Liu L N, Wu J X, Wu L Y, et al. Phase-selective synthesis of 1T’ MoS2 monolayers and heterophase bilayers. Nat Mater, 2018, 17, 1108 doi: 10.1038/s41563-018-0187-1
[97]
Zheng J Y, Yan X X, Lu Z X, et al. High-mobility multilayered MoS2 flakes with low contact resistance grown by chemical vapor deposition. Adv Mater, 2017, 29(13), 1604540 doi: 10.1002/adma.201604540
[98]
Gong C, Colombo L, Wallace R M, et al. The unusual mechanism of partial fermi level pinning at metal –MoS2 interfaces. Nano Lett, 2014, 14(4), 1714 doi: 10.1021/nl403465v
[99]
Saidi W A. Trends in the adsorption and growth morphology of metals on the MoS2 (001) surface. Cryst Growth Des, 2015, 15(7), 3190 doi: 10.1021/acs.cgd.5b00269
[100]
Meng L J, Ma Y, Si K P, et al. Recent advances of phase engineering in group VI transition metal dichalcogenides. Tungsten, 2019, 1, 46 doi: 10.1007/s42864-019-00012-x
[101]
Li J, Yang X D, Liu Y, et al. General synthesis of two-dimensional van der Waals heterostructure arrays. Nature, 2020, 579, 368 doi: 10.1038/s41586-020-2098-y
  • Search

    Advanced Search >>

    GET CITATION

    shu

    Export: BibTex EndNote

    Article Metrics

    Article views: 7427 Times PDF downloads: 472 Times Cited by: 0 Times

    History

    Received: 26 March 2020 Revised: 01 April 2020 Online: Accepted Manuscript: 27 May 2020Uncorrected proof: 01 June 2020Published: 02 July 2020

    Catalog

      Email This Article

      User name:
      Email:*请输入正确邮箱
      Code:*验证码错误
      Peng Zhang, Yiwei Zhang, Yi Wei, Huaning Jiang, Xingguo Wang, Yongji Gong. Contact engineering for two-dimensional semiconductors[J]. Journal of Semiconductors, 2020, 41(7): 071901. doi: 10.1088/1674-4926/41/7/071901 P Zhang, Y W Zhang, Y Wei, H N Jiang, X G Wang, Y J Gong, Contact engineering for two-dimensional semiconductors[J]. J. Semicond., 2020, 41(7): 071901. doi: 10.1088/1674-4926/41/7/071901.Export: BibTex EndNote
      Citation:
      Peng Zhang, Yiwei Zhang, Yi Wei, Huaning Jiang, Xingguo Wang, Yongji Gong. Contact engineering for two-dimensional semiconductors[J]. Journal of Semiconductors, 2020, 41(7): 071901. doi: 10.1088/1674-4926/41/7/071901

      P Zhang, Y W Zhang, Y Wei, H N Jiang, X G Wang, Y J Gong, Contact engineering for two-dimensional semiconductors[J]. J. Semicond., 2020, 41(7): 071901. doi: 10.1088/1674-4926/41/7/071901.
      Export: BibTex EndNote

      Contact engineering for two-dimensional semiconductors

      doi: 10.1088/1674-4926/41/7/071901
      More Information
      • Corresponding author: Email: yongjigong@buaa.edu.cn
      • Received Date: 2020-03-26
      • Revised Date: 2020-04-01
      • Published Date: 2020-07-01

      Catalog

        /

        DownLoad:  Full-Size Img  PowerPoint
        Return
        Return