Surface charge transfer doping (SCTD) is widely recognized as an effective and non-destructive method for modulating the electrical properties of atomically thin transition metal dichalcogenides (TMDs), capitalizing on their distinctive two-dimensional (2D) structure. Nevertheless, the challenges of achieving precise area-selective doping using conventional methods, such as dopant vaporization, have impeded the advancement of practical optoelectronic and electronic devices based on TMDs. Herein, we propose a simple and reliable area-selective SCTD strategy to facilitate transfer, doping, and encapsulation simultaneously during the polyvinyl alcohol (PVA)-assistant transfer process. The electrical performance of PVA-doped molybdenum disulfide (MoS2) field-effect transistor (FET) exhibited significant enhancement, with carrier concentrations reaching up to 1013 cm−2, on-state currents increasing to 10 μA·μm−1, and on/off ratios attaining a remarkable value of 107. Optical photothermal infrared (O-PTIR) spectroscopy was employed to elaborate the intrinsic temperature-dependent doping mechanism. The functionalization of MoS2 FETs was successfully achieved by introducing a hexagonal boron nitride (hBN) capping layer to define the doping area, enabling the creation of a homojunction with a rectification ratio of 106, an inverter fabricated within a single channel, and a Schottky barrier as low as 30.17 meV at the Au/MoS2 interface. This area-selective SCTD strategy, enabled by the PVA-assisted transfer process, offers a reliable, efficient, and economical approach for tailoring the functionalities of TMD-based devices, demonstrating substantial potential for diverse electronic applications.
Das, S.; Sebastian, A.; Pop, E.; McClellan, C. J.; Franklin, A. D.; Grasser, T.; Knobloch, T.; Illarionov, Y.; Penumatcha, A. V.; Appenzeller, J. et al. Transistors based on two-dimensional materials for future integrated circuits. Nat. Electron. 2021, 4, 786–799.
Zhu, W. J.; Low, T.; Wang, H.; Ye, P. D.; Duan, X. F. Nanoscale electronic devices based on transition metal dichalcogenides. 2D Mater. 2019, 6, 032004.
Mak, K. F.; Lee, C.; Hone, J.; Shan, J.; Heinz, T. F. Atomically Thin MoS2: A new direct-gap semiconductor. Phys. Rev. Lett. 2010, 105, 136805.
Qian, F. S.; Bu, X. B.; Wang, J. J.; Mao, J. Y.; Han, S. T.; Zhou, Y. Transistors and logic circuits enabled by 2D transition metal dichalcogenides: A state-of-the-art survey. J. Mater. Chem. C 2022, 10, 17002–17026.
Sheng, C. M.; Dong, X. Q.; Zhu, Y. X.; Wang, X. Y.; Chen, X. Y.; Xia, Y.; Xu, Z. H.; Zhou, P.; Wan, J.; Bao, W. Z. Two-dimensional semiconductors: From device processing to circuit integration. Adv. Funct. Mater. 2023, 33, 2304778.
Daus, A.; Vaziri, S.; Chen, V.; Köroğlu, Ç.; Grady, R. W.; Bailey, C. S.; Lee, H. R.; Schauble, K.; Brenner, K.; Pop, E. High-performance flexible nanoscale transistors based on transition metal dichalcogenides. Nat. Electron. 2021, 4, 495–501.
Fan, D. X.; Li, W. S.; Qiu, H.; Xu, Y. F.; Gao, S.; Liu, L.; Li, T. T.; Huang, F. T.; Mao, Y.; Zhou, W. B. et al. Two-dimensional semiconductor integrated circuits operating at gigahertz frequencies. Nat. Electron. 2023, 6, 879–887.
Wickramaratne, D.; Zahid, F.; Lake, R. K. Electronic and thermoelectric properties of few-layer transition metal dichalcogenides. J. Chem. Phys 2014, 140, 124710.
Yoon, Y.; Ganapathi, K.; Salahuddin, S. How good can monolayer MoS2 transistors be. Nano Lett. 2011, 11, 3768–3773.
Ye, Z. M.; Tan, C.; Huang, X. L.; Ouyang, Y.; Yang, L.; Wang, Z. G.; Dong, M. D. Emerging MoS2 wafer-scale technique for integrated circuits. Nano-Micro Lett. 2023, 15, 38.
Kang, Y. B.; Jeon, D.; Kim, T. Local mapping of the thickness-dependent dielectric constant of MoS2. J. Phys. Chem. C 2021, 125, 3611–3615.
Xie, L.; Liao, M. Z.; Wang, S. P.; Yu, H.; Du, L. J.; Tang, J.; Zhao, J.; Zhang, J.; Chen, P.; Lu, X. B. et al. Graphene-contacted ultrashort channel monolayer MoS2 transistors. Adv. Mater. 2017, 29, 1702522.
Zhang, X. D.; Huang, C. X.; Li, Z. Y.; Fu, J.; Tian, J. R.; Ouyang, Z. P.; Yang, Y. L.; Shao, X.; Han, Y. L.; Qiao, Z. H. et al. Reliable wafer-scale integration of two-dimensional materials and metal electrodes with van der Waals contacts. Nat. Commun. 2024, 15, 4619.
Kwon, J.; Seol, M.; Yoo, J.; Ryu, H.; Ko, D. S.; Lee, M. H.; Lee, E. K.; Yoo, M. S.; Lee, G. H.; Shin, H. J. et al. 200-mm-wafer-scale integration of polycrystalline molybdenum disulfide transistors. Nat. Electron. 2024, 7, 356–364.
Xu, H.; Zhang, H. M.; Guo, Z. X.; Shan, Y. W.; Wu, S. W.; Wang, J. L.; Hu, W. D.; Liu, H. Q.; Sun, Z. Z.; Luo, C. et al. High-performance wafer-scale MoS2 transistors toward practical application. Small 2018, 14, 1803465.
Lu, Z. Y.; Chen, Y.; Dang, W. Q.; Kong, L. A.; Tao, Q. Y.; Ma, L. K.; Lu, D. L.; Liu, L. T.; Li, W. Y.; Li, Z. W. et al. Wafer-scale high- κ dielectrics for two-dimensional circuits via van der Waals integration. Nat. Commun. 2023, 14, 2340.
Wang, H.; Yu, L. L.; Lee, Y. H.; Shi, Y. M.; Hsu, A.; Chin, M. L.; Li, L. J.; Dubey, M.; Kong, J.; Palacios, T. Integrated circuits based on bilayer MoS2 transistors. Nano Lett. 2012, 12, 4674–4680.
Meng, W. Q.; Xu, F. F.; Yu, Z. H.; Tao, T.; Shao, L. W.; Liu, L.; Li, T. T.; Wen, K. C.; Wang, J. P.; He, L. B. et al. Three-dimensional monolithic micro-LED display driven by atomically thin transistor matrix. Nat. Nanotechnol. 2021, 16, 1231–1236.
Loh, L.; Zhang, Z. P.; Bosman, M.; Eda, G. Substitutional doping in 2D transition metal dichalcogenides. Nano Res. 2021, 14, 1668–1681.
Chen, Y. F.; Xi, J. Y.; Dumcenco, D. O.; Liu, Z.; Suenaga, K.; Wang, D.; Shuai, Z. G.; Huang, Y. S.; Xie, L. M. Tunable band gap photoluminescence from atomically thin transition-metal dichalcogenide alloys. ACS Nano 2013, 7, 4610–4616.
Azcatl, A.; Qin, X. Y.; Prakash, A.; Zhang, C. X.; Cheng, L. X.; Wang, Q. X.; Lu, N.; Kim, M. J.; Kim, J.; Cho, K. et al. Covalent nitrogen doping and compressive strain in MoS2 by remote N2 plasma exposure. Nano Lett. 2016, 16, 5437–5443.
Kim, Y.; Bark, H.; Kang, B.; Lee, C. Wafer-scale substitutional doping of monolayer MoS2 films for high-performance optoelectronic devices. ACS Appl. Mater. Interfaces 2019, 11, 12613–12621.
Wang, Y. N.; Zheng, Y.; Han, C.; Chen, W. Surface charge transfer doping for two-dimensional semiconductor-based electronic and optoelectronic devices. Nano Res. 2021, 14, 1682–1697.
Sunwoo, H.; Choi, W. Tunable, stable, and reversible n-type doping of MoS2 via thermal treatment in N-methyl-2-pyrrolidone. Nanotechnology 2022, 33, 50LT01.
Fang, H.; Tosun, M.; Seol, G.; Chang, T. C.; Takei, K.; Guo, J.; Javey, A. Degenerate n-doping of few-layer transition metal dichalcogenides by potassium. Nano Lett. 2013, 13, 1991–1995.
Ryu, J. H.; You, Y. G.; Kim, S. W.; Hong, J. H.; Na, J. H.; Jhang, S. H. Effect of Al2O3 deposition on carrier mobility and ambient stability of few-layer MoS2 field effect transistors. Curr. Appl. Phys. 2020, 20, 363–365.
Chuang, S.; Battaglia, C.; Azcatl, A.; McDonnell, S.; Kang, J. S.; Yin, X. T.; Tosun, M.; Kapadia, R.; Fang, H.; Wallace, R. M. et al. MoS2 P-type transistors and diodes enabled by high work function MoO X contacts. Nano Lett. 2014, 14, 1337–1342.
Liu, Y.; Guo, J.; Zhu, E. B.; Liao, L.; Lee, S. J.; Ding, M. N.; Shakir, I.; Gambin, V.; Huang, Y.; Duan, X. F. Approaching the Schottky–Mott limit in van der Waals metal-semiconductor junctions. Nature 2018, 557, 696–700.
Liu, L. T.; Kong, L. G.; Li, Q. Y.; He, C. L.; Ren, L. W.; Tao, Q. Y.; Yang, X. D.; Lin, J.; Zhao, B.; Li, Z. W. et al. Transferred van der Waals metal electrodes for sub-1-nm MoS2 vertical transistors. Nat. Electron. 2021, 4, 342–347.
Hong, M. Y.; Zhang, X. K.; Geng, Y.; Wang, Y. N.; Wei, X. F.; Gao, L.; Yu, H. H.; Cao, Z. H.; Zhang, Z.; Zhang, Y. Universal transfer of full-class metal electrodes for barrier-free two-dimensional semiconductor contacts. InfoMat 2024, 6, e12491.
Jung, Y.; Choi, M. S.; Nipane, A.; Borah, A.; Kim, B.; Zangiabadi, A.; Taniguchi, T.; Watanabe, K.; Yoo, W. J.; Hone, J. et al. Transferred via contacts as a platform for ideal two-dimensional transistors. Nat. Electron. 2019, 2, 187–194.
Lim, D.; Kannan, E. S.; Lee, I.; Rathi, S.; Li, L. J.; Lee, Y.; Khan, M. A.; Kang, M.; Park, J.; Kim, G. H. High performance MoS2-based field-effect transistor enabled by hydrazine doping. Nanotechnology 2016, 27, 225201.
Kung, Y. C.; Hosseini, N.; Dumcenco, D.; Fantner, G. E.; Kis, A. Air and water-stable n-type doping and encapsulation of flexible MoS2 devices with SU8. Adv. Electron. Mater. 2019, 5, 1800492.
Ogura, H.; Kaneda, M.; Nakanishi, Y.; Nonoguchi, Y.; Pu, J.; Ohfuchi, M.; Irisawa, T.; Lim, H. E.; Endo, T.; Yanagi, K. et al. Air-stable and efficient electron doping of monolayer MoS2 by salt-crown ether treatment. Nanoscale 2021, 13, 8784–8789.
Heo, K.; Jo, S. H.; Shim, J.; Kang, D. H.; Kim, J. H.; Park, J. H. Stable and reversible triphenylphosphine-based n-type doping technique for molybdenum disulfide (MoS2). ACS Appl. Mater. Interfaces 2018, 10, 32765–32772.
Kang, J. H.; Liu, W.; Banerjee, K. High-performance MoS2 transistors with low-resistance molybdenum contacts. Appl. Phys. Lett. 2014, 104, 093106.
Cheng, R.; Jiang, S.; Chen, Y.; Liu, Y.; Weiss, N.; Cheng, H. C.; Wu, H.; Huang, Y.; Duan, X. F. Few-layer molybdenum disulfide transistors and circuits for high-speed flexible electronics. Nat. Commun. 2014, 5, 5143.
Nam, H.; Wi, S.; Rokni, H.; Chen, M. K.; Priessnitz, G.; Lu, W.; Liang, X. G. MoS2 transistors fabricated via plasma-assisted nanoprinting of few-layer MoS2 flakes into large-area arrays. ACS Nano 2013, 7, 5870–5881.
Chakraborty, B.; Matte, H. S. S. R.; Sood, A. K.; Rao, C. N. R. Layer-dependent resonant Raman scattering of a few layer MoS2. J. Raman Spectrosc. 2013, 44, 92–96.
Lockhart de la Rosa, C. J.; Nourbakhsh, A.; Heyne, M.; Asselberghs, I.; Huyghebaert, C.; Radu, I.; Heyns, M.; De Gendt, S. Highly efficient and stable MoS2 FETs with reversible n-doping using a dehydrated poly(vinyl-alcohol) coating. Nanoscale 2017, 9, 258–265.
Kiriya, D.; Tosun, M.; Zhao, P. D.; Kang, J. S.; Javey, A. Air-stable surface charge transfer doping of MoS2 by benzyl viologen. J. Am. Chem. Soc. 2014, 136, 7853–7856.
Guo, W. X.; Li, M. G.; Wu, X. X.; Liu, Y. L.; Ou, T. J.; Xiao, C.; Qiu, Z. J.; Zheng, Y.; Wang, Y. W. Nonvolatile n-type doping and metallic state in multilayer-MoS2 induced by hydrogenation using ionic-liquid gating. Nano Lett. 2022, 22, 8957–8965.
Li, M. G.; Yao, J. D.; Liu, Y. L.; Wu, X. X.; Yu, Y.; Xing, B. R.; Yan, X. Y.; Guo, W. X.; Tan, M. Q.; Sha, J. et al. Air stable and reversible n-type surface functionalization of MoS2 monolayer using Arg and Lys amino acids. J. Mater. Chem. C 2020, 8, 12181–12188.
Yang, H. G.; Xu, S. B.; Jiang, L.; Dan, Y. Thermal decomposition behavior of poly (vinyl alcohol) with different hydroxyl content. J. Macromol. Sci. B 2012, 51, 464–480.
Fernández, M. D.; Fernández, M. J. Thermal degradation of copolymers from vinyl acetate and vinyl alcohol. J. Therm. Anal. Calorim 2008, 92, 829–837.
Anders, H.; Zimmermann, H. A comparison of the thermal degradation behaviours of poly(vinyl acetate), poly(vinyl alcohol) and poly(vinyl chloride). Polym. Degrad. Stab. 1987, 18, 111–122.
Tsuchiya, Y.; Sumi, K. Thermal decomposition products of poly(vinyl alcohol). J. Polym. Sci. A: Polym. Chem. 1969, 7, 3151–3158.
Holland, B. J.; Hay, J. N. The thermal degradation of poly(vinyl alcohol). Polymer 2001, 42, 6775–6783.
Thomas, P. S.; Guerbois, J. P.; Russell, G. F.; Briscoe, B. J. FTIR study of the thermal degradation of poly(vinyl alcohol). J. Therm. Anal. Calorim 2001, 64, 501–508.
Yuan, Y. H.; Teja, A. S. Quantification of specific interactions between CO2 and the carbonyl group in polymers via ATR-FTIR measurements. J. Supercrit. Fluids 2011, 56, 208–212.
Ma, G. Y.; Wang, L.; Wang, X. R.; Wang, C. J.; Li, X.; Li, L.; Ma, H. F. Preparation and properties of poly(vinyl acetate) adhesive modified with vinyl versatate. Molecules 2023, 28, 6634.
Ţucureanu, V.; Matei, A.; Avram, A. M. FTIR spectroscopy for carbon family study. Crit. Rev. Anal. Chem. 2016, 46, 502–520.
Michaelson, H. B. The work function of the elements and its periodicity. J. Appl. Phys. 1977, 48, 4729–4733.
Yang, H.; Heo, J.; Park, S.; Song, H. J.; Seo, D. H.; Byun, K. E.; Kim, P.; Yoo, I.; Chung, H. J.; Kim, K. Graphene barristor, a triode device with a gate-controlled Schottky barrier. Science 2012, 336, 1140–1143.
Ang, Y. S.; Yang, H. Y.; Ang, L. K. Universal scaling laws in Schottky heterostructures based on two-dimensional materials. Phys. Rev. Lett. 2018, 121, 056802.
Zhao, X. M.; Xia, C. J.; Li, L. B.; Wang, A. X.; Cao, D. Z.; Zhang, B. Y.; Fang, Q. L. Tuning the Schottky barrier height in single- and bi-layer graphene-inserted MoS2/metal contacts. Sci. Rep. 2024, 14, 20905.
Choi, D.; Jeon, J.; Park, T. E.; Ju, B. K.; Lee, K. Y. Schottky barrier height engineering on MoS2 field-effect transistors using a polymer surface modifier on a contact electrode. Discov. Nano 2023, 18, 80.
Pan, Y. Y.; Gu, J. H.; Tang, H.; Zhang, X. Y.; Li, J. Z.; Shi, B. W.; Yang, J.; Zhang, H.; Yan, J. H.; Liu, S. Q. et al. Reexamination of the Schottky barrier heights in monolayer MoS2 field-effect transistors. ACS Appl. Nano Mater. 2019, 2, 4717–4726.
Kaushik, N.; Nipane, A.; Basheer, F.; Dubey, S.; Grover, S.; Deshmukh, M. M.; Lodha, S. Schottky barrier heights for Au and Pd contacts to MoS2. Appl. Phys. Lett. 2014, 105, 113505.
Min, K. A.; Park, J.; Wallace, R. M.; Cho, K.; Hong, S. Reduction of Fermi level pinning at Au–MoS2 interfaces by atomic passivation on Au surface. 2D Mater. 2017, 4, 015019.
English, C. D.; Shine, G.; Dorgan, V. E.; Saraswat, K. C.; Pop, E. Improved contacts to MoS2 transistors by ultra-high vacuum metal deposition. Nano Lett. 2016, 16, 3824–3830.