Van der Waals heterostructures and devices

Nature Reviews Materials - Tập 1 Số 9
Yuan Liu1, Nathan O. Weiss1, Xidong Duan2, Horng-Long Cheng1, Yu Huang1, Xiangfeng Duan3
1Department of Materials Science and Engineering, University of California, Los Angeles, 90095, California, USA
2State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, Hunan, P. R. China
3Department of Chemistry and Biochemistry, University of California, Los Angeles, 90095, California, USA

Tóm tắt

Từ khóa


Tài liệu tham khảo

Novoselov, K. S. et al. A roadmap for graphene. Nature 490, 192–200 (2012).

Schwierz, F. Graphene transistors. Nat. Nanotechnol. 5, 487–496 (2010).

Weiss, N. O. et al. Graphene: an emerging electronic material. Adv. Mater. 24, 5782–5825 (2012).

Wang, Q. H., Kalantar-Zadeh, K., Kis, A., Coleman, J. N. & Strano, M. S. Electronics and optoelectronics of two-dimensional transition metal dichalcogenides. Nat. Nanotechnol. 7, 699–712 (2012).

Geim, A. K. & Grigorieva, I. V. Van der Waals heterostructures. Nature 499, 419–425 (2013). A comprehensive review of stacking 2DLMs into diverse vdWHs.

Chhowalla, M. et al. The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets. Nat. Chem. 5, 263–275 (2013).

Fiori, G. et al. Electronics based on two-dimensional materials. Nat. Nanotechnol. 9, 768–779 (2013).

Jariwala, D., Sangwan, V. K., Lauhon, L. J., Marks, T. J. & Hersam, M. C. Emerging device applications for semiconducting two-dimensional transition metal dichalcogenides. ACS Nano 8, 1102–1120 (2014).

Zhang, H. Ultrathin two-dimensional nanomaterials. ACS Nano 9, 9451–9469 (2015).

Liu, Y. et al. Plasmon resonance enhanced multicolour photodetection by graphene. Nat. Commun. 2, 579 (2011).

Konstantatos, G. et al. Hybrid graphene–quantum dot phototransistors with ultrahigh gain. Nat. Nanotechnol. 7, 363–368 (2012).

Liao, L. et al. High-k oxide nanoribbons as gate dielectrics for high mobility top-gated graphene transistors. Proc. Natl Acad. Sci. USA 107, 6711–6715 (2010). This study represents one the first reports of van der Waals integration of 2DLM (graphene) with other diverse nanostructures, which can minimize the damage to 2DLM atomic lattices and retain their intrinsic electronic properties.

Liao, L. et al. High-speed graphene transistors with a self-aligned nanowire gate. Nature 467, 305–308 (2010).

Dean, C. R. et al. Boron nitride substrates for high-quality graphene electronics. Nat. Nanotechnol. 5, 722–726 (2010). This study represents one of the earliest report of van der Waals integration of two different 2DLMs to create 2DLM vdWHs.

Britnell, L. et al. Electron tunneling through ultrathin boron nitride crystalline barriers. Nano Lett. 12, 1707–1710 (2012).

Withers, F. et al. Light-emitting diodes by band-structure engineering in van der Waals heterostructures. Nat. Mater. 14, 301–306 (2015).

Geim, A. K. & Novoselov, K. S. The rise of graphene. Nat. Mater. 6, 183–191 (2007).

Lee, C. et al. Measurement of the elastic properties and intrinsic strength of monolayer graphene. Science 321, 385–388 (2008).

Neto, A. C. et al. The electronic properties of graphene. Rev. Mod. Phys. 81, 109 (2009).

Novoselov, K. S. et al. Unconventional quantum Hall effect and Berry's phase of 2π in bilayer graphene. Nat. Phys. 2, 177–180 (2006).

Zhang, Y. et al. Direct observation of a widely tunable bandgap in bilayer graphene. Nature. 459, 820–823 (2009).

Luican, A. et al. Single layer behavior and its breakdown in twisted graphene layers. Phys. Rev. Lett. 106, 126802 (2011).

Mayorov, A. S. et al. Micrometer-scale ballistic transport in encapsulated graphene at room temperature. Nano Lett. 11, 2396–2399 (2011).

Meric, I. et al. in 2011 IEEE International Electron Devices Meeting 2.1.1–2.1.4 (Washington, 2011).

Ci, L. et al. Atomic layers of hybridized boron nitride and graphene domains. Nat. Mater. 9, 430–43 5 (2010).

Duan, X., Wang, C., Pan, A., Yu, R. & Duan, X. Two-dimensional transition metal dichalcogenides as atomically thin semiconductors: opportunities and challenges. Chem. Soc. Rev. 44, 8859–8876 (2015).

Mak, K. F., Lee, C., Hone, J., Shan, J. & Heinz, T. F. Atomically thin MoS2: a new direct-gap semiconductor. Phys. Rev. Lett. 105, 136805 (2010). This represents one of the earliest studies reporting the indirect-to-direct band transition in MoS2, which ignited the intense interest in TMD materials.

Radisavljevic, B., Radenovic, A., Brivio, J., Giacometti, V. & Kis, A. Single-layer MoS2 transistors. Nat. Nanotechnol. 6, 147–150 (2011).

Reale, F. Sharda, K. & Mattevi, C. et al. From bulk crystals to atomically thin layers of group VI transition metal dichalcogenides vapour phase synthesis. Appl. Mater. Today 3, 11–22 (2016).

Lee, Y. H. et al. Synthesis of large area MoS2 atomic layers with chemical vapor deposition. Adv. Mater. 24, 2320–2325 (2012).

Shaw, J. C. et al. Chemical vapor deposition growth of monolayer MoSe2 nanosheets. Nano. Res. 7, 511–517 (2014).

Zhou, H. et al. Large area growth and electrical properties of p-type WSe2 atomic layers. Nano. Lett. 15, 709–713 (2014).

Kang, K. et al. High-mobility three-atom-thick semiconducting films with wafer-scale homogeneity. Nature 520, 656–660 (2015).

Mak, K. F., McGill, K. L., Park, J. & McEuen, P. L. The valley Hall effect in MoS2 transistors. Science 344, 1489–1492 (2014).

Zeng, H., Dai, J., Yao, W., Xiao, D. & Cui, X. Valley polarization in MoS2 monolayers by optical pumping. Nat. Nanotechnol. 7, 490–493 (2012).

Ye, J. et al. Superconducting dome in a gate-tuned band insulator. Science 338, 1193–1196 (2012).

Kong, D. & Cui, Y. Opportunities in chemistry and materials science for topological insulators and their nanostructures. Nat. Chem. 3, 845–849 (2011).

Sun, Y. et al. Atomically thick bismuth selenide freestanding single layers achieving enhanced thermoelectric energy harvesting. J. Am. Chem. Soc. 134, 20294–20297 (2012).

Min, Y. et al. Surfactant-free scalable synthesis of Bi2Te3 and Bi2Se3 nanoflakes and enhanced thermoelectric properties of their nanocomposites. Adv. Mater. 25, 1425–1429 (2013).

Hong, M., Chen, Z., Yang, L., Han, G. & Zou, J. Enhanced thermoelectric performance of ultrathin Bi2Se3 nanosheets through thickness control. Adv. Electron. Mater. 1, 1500025 (2015).

Naguib, M., Mochalin, V. N., Barsoum, M. W. & Gogotsi, Y. 25th anniversary article: MXenes: a new family of two-dimensional materials. Adv. Mater. 26, 992–1005 (2014).

Qiao, J., Kong, X., Hu, Z.-X., Yang, F. & Ji, W. High-mobility transport anisotropy and linear dichroism in few-layer black phosphorus. Nat. Commun. 5, 4475 (2014).

Liu, H. et al. Phosphorene: an unexplored 2D semiconductor with a high hole mobility. ACS Nano 8, 4033–4041 (2014).

Li, L. et al. Black phosphorus field-effect transistors. Nat. Nanotechnol. 8, 4033–4041 (2014).

Osada, M. & Sasaki, T. Exfoliated oxide nanosheets: new solution to nanoelectronics. J. Mater. Chem. 19, 2503–2511 (2009).

Subramanian, M. et al. A new high-temperature superconductor: Bi2Sr3−xCax Cu2O8+y . Science 239, 1015–1017 (1988).

Wang, Q. & O'Hare, D. Recent advances in the synthesis and application of layered double hydroxide (LDH) nanosheets. Chem. Rev. 112, 4124–4155 (2012).

Colson, J. W. et al. Oriented 2D covalent organic famework thin films on single-layer graphene. Science 332, 228–231 (2011).

Duan, X. et al. Lateral epitaxial growth of two-dimensional layered semiconductor heterojunctions. Nat. Nanotechnol. 9, 1024–1030 (2014).

Nair, R. R. et al. Fluorographene: a two-dimensional counterpart of teflon. Small 6, 2877–2884 (2010).

Elias, D. C. et al. Control of graphene's properties by reversible hydrogenation: evidence for graphane. Science 323, 610–613 (2009).

Duan, X. et al. Synthesis of WS2xSe2−2x alloy nanosheets with composition-tunable electronic properties. Nano Lett. 16, 264–269 (2016).

Li, H. et al. Lateral growth of composition graded atomic layer MoS2(1−x) Se2x nanosheets. J. Am. Chem. Soc. 137, 5284–5287 (2015).

Zhang, W. et al. CVD synthesis of Mo(1−x)WxS2 and MoS2(1−x)Se2x alloy monolayers aimed at tuning the bandgap of molybdenum disulfide. Nanoscale 7, 13554–13560 (2015).

Feng, Q. et al. Growth of MoS2(1−x)Se2x (x = 0.41–1.00) monolayer alloys with controlled morphology by physical vapor deposition. ACS Nano 9, 7450–7455 (2015).

Li, M.-Y. et al. Epitaxial growth of a monolayer WSe2–MoS2 lateral pn junction with an atomically sharp interface. Science 349, 524–528 (2015).

Gong, Y. et al. Vertical and in-plane heterostructures from WS2/MoS2 monolayers. Nat. Mater. 13, 1135–1142 (2014).

Novoselov, K. S. et al. Electric field effect in atomically thin carbon films. Science 306, 666–669 (2004).

Novoselov, K. S. et al. Two-dimensional atomic crystals. Proc. Nati. Acad. Sci. USA 102, 10451–10453 (2005).

Nicolosi, V., Chhowalla, M., Kanatzidis, M. G., Strano, M. S. & Coleman, J. N. Liquid exfoliation of layered materials. Science 340, http://dx.doi.org/10.1126/science.1226419 (2013).

Halim, U. et al. A rational design of cosolvent exfoliation of layered materials by directly probing liquid–solid interaction. Nat. Commun. 4, 2213 (2013).

Lu, Q., Yu, Y., Ma, Q., Chen, B. & Zhang, H. 2D Transition-metal-dichalcogenide-nanosheet-based composites for photocatalytic and electrocatalytic hydrogen evolution reactions. Adv. Mater. 28, 1917–1933 (2016).

Song, L. et al. Large scale growth and characterization of atomic hexagonal boron nitride layers. Nano Lett. 10, 3209–3215 (2010).

Liu, L. et al. Heteroepitaxial growth of two-dimensional hexagonal boron nitride templated by graphene edges. Science 343, 163–167 (2014).

Yu, J. Li, J., Zhang, W. & Chang, H. Synthesis of high quality two-dimensional materials via chemical vapor deposition. Chem. Sci. 6, 6705–6716 (2015).

Lu, G. et al. Synthesis of large single-crystal hexagonal boron nitride grains on Cu–Ni alloy. Nat. Commun. 6, 6160 (2015).

Wu, T. et al. Fast growth of inch-sized single-crystalline graphene from a controlled single nucleus on Cu–Ni alloys. Nat. Mater. 15, 43–47 (2016).

Andres, C.-G. et al. Deterministic transfer of two-dimensional materials by all-dry viscoelastic stamping. 2D Mater. 1, 011002 (2014).

Zomer, P. J., Dash, S. P., Tombros, N. & Wees, B. J. A transfer technique for high mobility graphene devices on commercially available hexagonal boron nitride. Appl. Phys. Lett. 99, 232104 (2011).

Wang, L. et al. One-dimensional electrical contact to a two-dimensional material. Science. 342, 614–617 (2013). This study represents the first report of the edge-contact geometry for making contact to 2DLMs, which is important for constructing complex vdWH devices.

Haigh, S. J. et al. Cross-sectional imaging of individual layers and buried interfaces of graphene-based heterostructures and superlattices. Nat. Mater. 11, 764–767 (2012).

Yan, A. et al. Direct growth of single- and few-layer MoS2 on h-BN with preferred relative rotation angles. Nano Lett. 15, 6324–6331 (2015).

Woods, C. R. et al. Commensurate–incommensurate transition in graphene on hexagonal boron nitride. Nat. Phys. 10, 451–456 (2014).

Liu, Y. et al. Towards barrier free contact to molybdenum disulfide using graphene electrodes. Nano Lett. 15, 3030–3034 (2015). This study presents the highest FET mobility achieved in MoS2 using a barrier-free coplanar graphene contact, with a peak mobility of 1,300 cm2 V−1 s−1.

Cui, X. et al. Multi-terminal transport measurements of MoS2 using a van der Waals heterostructure device platform. Nat. Nanotechnol. 10, 534–540 (2015). This study presents the highest Hall mobility achieved in MoS2 using multiterminal staggered graphene contact, with a peak mobility of 34,000 cm2 V−1 s−1.

Avsar, A. et al. Air-stable transport in graphene-contacted, fully encapsulated ultrathin black phosphorus-based field-effect transistors. ACS Nano 9, 4138–4145 (2015).

Cheng, H. C. et al. Van der Waals heterojunction devices based on organohalide perovskites and two-dimensional materials. Nano Lett. 16, 367–373 (2016).

Fiori, G., Bruzzone, S. & Iannaccone, G. Very Large current modulation in vertical heterostructure graphene/hBN transistors. IEEE Trans. Electron Devices 60, 268–273 (2013).

Yankowitz, M. et al. Emergence of superlattice Dirac points in graphene on hexagonal boron nitride. Nat. Phys. 8, 382–386 (2012).

Xue, J. et al. Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride. Nat. Mater. 10, 282–285 (2011).

Zhao, W. et al. Evolution of electronic structure in atomically thin sheets of WS2 and WSe2 . ACS Nano 7, 791–797 (2012).

Das, S. et al. Tunable transport gap in phosphorene. Nano Lett. 14, 5733–5739 (2014).

Chiu, M.-H. et al. Spectroscopic signatures for interlayer coupling in MoS2–WSe2 van der Waals stacking. ACS Nano 8, 9649–9656 (2014).

Ponomarenko, L. A. et al. Tunable metal–insulator transition in double-layer graphene heterostructures. Nat. Phys. 7, 958–961 (2011).

Fang, H. et al. Strong interlayer coupling in van der Waals heterostructures built from single-layer chalcogenides. Proc. Nati. Acad. Sci. USA 111, 6198–6202 (2014).

Liu, K. et al. Evolution of interlayer coupling in twisted molybdenum disulfide bilayers. Nat. Commun. 5, 4966 (2014).

Hong, X. et al. Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures. Nat. Nanotechnol. 9, 682–686 (2014).

Rivera, P. et al. Observation of long-lived interlayer excitons in monolayer MoSe2–WSe2 heterostructures. Nat. Commun. 6, 6242 (2015).

Ceballos, F., Bellus, M. Z., Chiu, H.-Y. & Zhao, H. Probing charge transfer excitons in a MoSe2–WS2 van der Waals heterostructure. Nanoscale 7, 17523–17528 (2015).

Bellus, M. Z., Ceballos, F., Chiu, H.-Y. & Zhao, H. Tightly bound trions in transition metal dichalcogenide heterostructures. ACS Nano 9, 6459–6464 (2015).

Cheng, R. et al. Few-layer molybdenum disulfide transistors and circuits for high-speed flexible electronics. Nat. Commun. 5, 5143 (2014). This study reports the highest performance MoS2 transistors with self-aligned geometry and optimized contact to enable an intrinsic cut-off frequency of 42 GHz, and a maximum power-gain frequency of 50 GHz.

Allain, A., Kang, J., Banerjee, K. & Kis, A. Electrical contacts to two-dimensional semiconductors. Nat. Mater. 14, 1195–1205 (2015).

Das, S., Chen, H.-Y., Penumatcha, A. V. & Appenzeller, J. High performance multilayer MoS2 transistors with scandium contacts. Nano Lett. 13, 100–105 (2012).

Qu, D., Liu, X., Ahmed, F., Lee, D. & Yoo, W. J. Self-screened high performance multi-layer MoS2 transistor formed by using a bottom graphene electrode. Nanoscale 7, 19273–19281 (2015).

Roy, T. et al. Field-effect transistors built from all two-dimensional material components. ACS Nano 8, 6259–6264 (2014).

Chuang, H.-J. et al. High mobility WSe2 p-and n-type field-effect transistors contacted by highly doped graphene for low-resistance contacts. Nano Lett. 14, 3594–3601 (2014).

Das, S., Gulotty, R., Sumant, A. V. & Roelofs, A. All two-dimensional, flexible, transparent, and thinnest thin film transistor. Nano Lett. 14, 2861–2866 (2014).

Yoon, J. et al. Highly flexible and transparent multilayer MoS2 transistors with graphene electrodes. Small 9, 3295–3300 (2013).

Yu, L. et al. Graphene/MoS2 hybrid technology for large-scale two-dimensional electronics. Nano Lett. 14, 3055–3063 (2014).

Lee, G.-H. et al. Highly stable, dual-gated MoS2 transistors encapsulated by hexagonal noron nitride with gate-controllable contact, resistance, and threshold Voltage. ACS Nano 9, 7019–7026 (2015).

Das, S. & Appenzeller, J. Where does the current flow in two-dimensional layered systems? Nano Lett. 13, 3396–3402 (2013).

Das, S. & Appenzeller, J. Screening and interlayer coupling in multilayer MoS2 . Phys. Stat. Sol. 7, 268–273 (2013).

Wang, Y. et al. Does p-type ohmic contact exist in WSe2–metal interfaces? Nanoscale 8, 1179–1191 (2016).

Kang, J., Liu, W. & Banerjee, K. High-performance MoS2 transistors with low-resistance molybdenum contacts. Appl. Phys. Lett. 104, 093106 (2014).

Yang, L. et al. Chloride molecular doping technique on 2D materials: WS2 and MoS2 . Nano Lett. 14, 6275–6280 (2014).

Kappera, R. et al. Phase-engineered low-resistance contacts for ultrathin MoS2 transistors. Nat. Mater. 13, 1128–1134 (2014).

Kiriya, D., Tosun, M., Zhao, P., Kang, J. S. & Javey, A. Air-stable surface charge transfer doping of MoS2 by benzyl viologen. J. Am. Chem. Soc. 136, 7853–7856 (2014).

Leong, W. S. et al. Low resistance metal contacts to MoS2 devices with nickel-etched-graphene electrodes. ACS Nano 9, 869–877 (2014).

Du, Y. et al. Field-effect transistors with graphene/metal heterocontacts. IEEE Electron Device Lett. 35, 599–601 (2014).

Jena, D., Banerjee, K. & Xing, G. H. 2D crystal semiconductors: intimate contacts. Nat. Mater. 13, 1076–1078 (2014).

English, C. D., Shine, G., Dorgan, V. E., Saraswat, K. C. & Pop, E. in 72nd Device Research Conference 193–194 (Santa Barbara, 2014).

Ma, Y., Dai, Y., Guo, M., Niu, C. & Huang, B. Graphene adhesion on MoS2 monolayer: an ab initio study. Nanoscale 3, 3883–3887 (2011).

Kang, J., Liu, W., Sarkar, D., Jena, D. & Banerjee, K. Computational study of metal contacts to monolayer transition-metal dichalcogenide semiconductors. Phys. Rev. X 4, 031005 (2014).

Cho, S. et al. Phase patterning for ohmic homojunction contact in MoTe2 . Science 349, 625–628 (2015).

Li, X. et al. Performance potential and limit of MoS2 transistors. Adv. Mater. 27, 1547–1552 (2015).

Yu, W. J. et al. Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters. Nat. Mater. 12, 246–252 (2013).

Moriya, R. et al. Vertical field effect transistor based on graphene/transition metal dichalcogenide van der Waals heterostructure. ECS Trans. 69, 357–363 (2015).

Georgiou, T. et al. Vertical field-effect transistor based on graphene–WS2 heterostructures for flexible and transparent electronics. Nat. Nanotechnol. 8, 100–103 (2013).

Moriya, R. et al. Large current modulation in exfoliated-graphene/MoS2/metal vertical heterostructures. Appl. Phys. Lett. 105, 083119 (2014).

Moriya, R. et al. Influence of the density of states of graphene on the transport properties of graphene/MoS2/metal vertical field-effect transistors. Appl. Phys. Lett. 106, 223103 (2015).

Sata, Y. et al. Electric field modulation of Schottky barrier height in graphene/MoSe2 van der Waals heterointerface. Appl. Phys. Lett. 107, 023109 (2015).

Yang, H. et al. Graphene barristor, a triode device with a gate-controlled Schottky barrier. Science 336, 1140–1143 (2012). This is the first report of a graphene-based vertical thermionic transistor, in which graphene is used as an active contact rather than the channel material.

Heo, J. et al. Graphene and thin-film semiconductor heterojunction transistors integrated on wafer scale for low-power electronics. Nano Lett. 13, 5967–5971 (2013).

Liu, Y. et al. Highly flexible electronics from scalable vertical thin film transistors. Nano Lett. 14, 1413–1418 (2014). This study demonstrates that the unique concept of graphene-based vertical transistors can enable thin-film electronics with unusual flexibility.

Parui, S. et al. Gate-controlled energy barrier at a graphene/molecular semiconductor junction. Adv. Funct. Mater. 25, 2972–2979 (2015).

Lemaitre, M. G. et al. Improved transfer of graphene for gated Schottky-junction, vertical, organic, field-effect transistors. ACS Nano 6, 9095–9102 (2012).

Hlaing, H. et al. Low-voltage organic electronics based on a gate-tunable injection barrier in vertical graphene–organic semiconductor heterostructures. Nano Lett. 15, 69–74 (2014).

He, D. et al. Two-dimensional quasi-freestanding molecular crystals for high-performance organic field-effect transistors. Nat. Commun. 5, 5162 (2014).

Liu, Y., Zhou, H., Weiss, N. O., Huang, Y. & Duan, X. High-performance organic vertical thin film transistor using graphene as a tunable contact. ACS Nano 9, 11102–11108 (2015).

Kim, K. et al. Structural and electrical investigation of C60-graphene vertical heterostructures. ACS Nano 9, 5922–5928 (2015).

Appenzeller, J., Lin, Y.-M., Knoch, J. & Avouris, P. Band-to-band tunneling in carbon nanotube field-effect transistors. Phys. Rev. Lett. 93, 196805 (2004).

Luryi, S. Quantum capacitance devices. Appl. Phys. Lett. 52, 501–503 (1988).

Britnell, L. et al. Field-effect tunneling transistor based on vertical graphene heterostructures. Science 335, 947–950 (2012). This is the first report of a graphene-based vertical tunnelling transistor, based on graphene–BN–graphene vdWHs.

Britnell, L. et al. Resonant tunnelling and negative differential conductance in graphene transistors. Nat. Commun. 4, 1794 (2013).

Mishchenko, A. et al. Twist-controlled resonant tunnelling in graphene/boron nitride/graphene heterostructures. Nat. Nanotechnol. 9, 808–813 (2014).

Greenaway, M. et al. Resonant tunnelling between the chiral Landau states of twisted graphene lattices. Nat. Phys. 11, 1057–1062 (2015).

Liu, Y. et al. High Current density vertical tunneling transistors from graphene/highly-doped silicon heterostructures. Adv. Mater. 28, 4120–4125 (2016).

Sze, S. M. & Ng, K. K. Physics of semiconductor devices (Wiley, 2006).

Ross, J. S. et al. Electrically tunable excitonic light-emitting diodes based on monolayer WSe2 p–n junctions. Nat. Nanotechnol. 9, 268–272 (2014).

Pospischil, A., Furchi, M. M. & Mueller, T. Solar-energy conversion and light emission in an atomic monolayer p–n diode. Nat. Nanotechnol. 9, 257–261 (2014).

Baugher, B. W. H., Churchill, H. O. H., Yang, Y. & Jarillo-Herrero, P. Optoelectronic devices based on electrically tunable p–n diodes in a monolayer dichalcogenide. Nat. Nanotechnol. 9, 262–267 (2014).

Sarkar, D. et al. A subthermionic tunnel field-effect transistor with an atomically thin channel. Nature 526, 91–95 (2015).

Roy, T. et al. Dual-gated MoS2/WSe2 van der Waals tunnel diodes and transistors. ACS Nano 9, 2071–2079 (2015).

Jariwala, D. et al. Gate-tunable carbon nanotube–MoS2 heterojunction pn diode. Proc. Natl. Acad. Sci. USA 110, 18076–18080 (2013).

Chuang, S. et al. Near-ideal electrical properties of InAs/WSe2 van der Waals heterojunction diodes. Appl. Phys. Lett. 102, 242101 (2013).

Furchi, M. M., Pospischil, A., Libisch, F., Burgdörfer, J. & Mueller, T. Photovoltaic effect in an electrically tunable van der Waals heterojunction. Nano Lett. 14, 4785–4791 (2014).

Shim, G. W. et al. Large-area single-layer MoSe2 and its van der Waals heterostructures. ACS Nano 8, 6655–6662 (2014).

Lee, C.-H. et al. Atomically thin p–n junctions with van der Waals heterointerfaces. Nat. Nanotechnol. 9, 676–681 (2014).

Yu, J. H. et al. Vertical heterostructure of two-dimensional MoS2 and WSe2 with vertically aligned layers. Nano Lett. 15, 1031–1035 (2015).

Deng, Y. et al. Black phosphorus–monolayer MoS2 van der Waals heterojunction p–n diode. ACS Nano 8, 8292–8299 (2014).

Cheng, R. et al. Electroluminescence and photocurrent generation from atomically sharp WSe2/MoS2 heterojunction p–n diodes. Nano Lett. 14, 5590–5597 (2014).

Jeon, P. J. et al. Enhanced device performances of WSe2–MoS2 van der Waals junction p–n diode by fluoropolymer encapsulation. J. Mater. Chem. C 3, 2751–2758 (2015).

Wang, F. et al. Tunable GaTe–MoS2 van der Waals pn junctions with novel optoelectronic performance. Nano Lett. 15, 7558–7566 (2015).

Liu, F. et al. Van der Waals p–n junction based on an organic–inorganic heterostructure. Adv. Funct. Mater. 25, 5865–5871 (2015).

Jariwala, D. et al. Large-area, low-voltage, antiambipolar heterojunctions from solution-processed semiconductors. Nano Lett. 15, 416–421 (2014).

Lam, K. T., Seol, G. & Guo, J. Operating principles of vertical transistors based on monolayer two-dimensional semiconductor heterojunctions. Appl. Phys. Lett. 105, 013112 (2014).

Gan, X. et al. Chip-integrated ultrafast graphene photodetector with high responsivity. Nat. Photonics 7, 883–887 (2013).

Pospischil, A. et al. CMOS-compatible graphene photodetector covering all optical communication bands. Nat. Photonics 7, 892–896 (2013).

Wang, X., Cheng, Z., Xu, K., Tsang, H. K. & Xu, J.-B. High-responsivity graphene/silicon-heterostructure waveguide photodetectors. Nat. Photonics 7, 888–891 (2013).

Shiue, R.-J. et al. High-responsivity graphene–boron nitride photodetector and autocorrelator in a silicon photonic integrated circuit. Nano Lett. 15, 7288–7293 (2015).

Urich, A., Unterrainer, K. & Mueller, T. Intrinsic response time of graphene photodetectors. Nano Lett. 11, 2804–2808 (2011).

Mak, K. F., Ju, L., Wang, F. & Heinz, T. F. Optical spectroscopy of graphene: from the far infrared to the ultraviolet. Solid State Commun. 152, 1341–1349 (2012).

Bonaccorso, F., Sun, Z., Hasan, T. & Ferrari, A. C. Graphene photonics and optoelectronics. Nat. Photonics 4, 611–622 (2010).

Echtermeyer, T. et al. Strong plasmonic enhancement of photovoltage in graphene. Nat. Commun. 2, 458 (2011).

Carvalho, A., Ribeiro, R. M. & Castro Neto, A. H. Band nesting and the optical response of two-dimensional semiconducting transition metal dichalcogenides. Phys. Rev. B 88, 115205 (2013).

Kozawa, D. et al. Photocarrier relaxation pathway in two-dimensional semiconducting transition metal dichalcogenides. Nat. Commun. 5, 4543 (2014).

Britnell, L. et al. Strong light-matter interactions in heterostructures of atomically thin films. Science 340, 1311–1314 (2013).

Yu, W. J et al. Highly efficient gate-tunable photocurrent generation in vertical heterostructures of layered materials. Nat. Nanotechnol. 8, 952–958 (2013).

Massicotte, M. et al. Picosecond photoresponse in van der Waals heterostructures. Nat. Nanotechnol. 11, 42–46 (2016).

Lopez-Sanchez, O. et al. Light generation and harvesting in a van der Waals heterostructure. ACS Nano 8, 3042–3048 (2014).

Yamakoshi, S., Sanada, T., Wada, O., Umebu, I. & Sakurai, T. Direct observation of electron leakage in InGaAsP/InP double heterostructure. Appl. Phys. Lett. 40, 144–146 (1982).

Withers, F. et al. WSe2 light-emitting tunneling transistors with enhanced brightness at room temperature. Nano Lett. 15, 8223–8228 (2015).

Li, D. et al. Electric-field-induced strong enhancement of electroluminescence in multilayer molybdenum disulfide. Nat. Commun. 6, 7509 (2015).

Liu, F. et al. High-sensitivity photodetectors based on multilayer GaTe flakes. ACS Nano 8, 752–760 (2014).

Julien, C., Chevy, A. & Siapkas, D. Optical properties of In2Se3 phases. Phys. Status Solidi A 118, 553–559 (1990).