Title: A lift-off method for wafer scale hetero-structuring of 2D materials
Abstract: The isolation of graphene [1] and closely related materials such as transition metal dichalcogenides [2], has sparked intensive worldwide research efforts towards the large scale deposition of 2D crystals and films [3][4]. So far there has been no clear winner method for the fabrication of wafer scale heterostructures in a low cost and facile manner, which is an imperative step towards the commercialization of 2D integrated circuits. Currently the techniques that have been reported in the literature employ epitaxial growth of single crystal TMDCs and mechanical stacking of CVD grown or exfoliated flakes resulting in 2D flake heterostructures [5][6]. Here we present a large-scale method for fabricating 2D heterostructures based on the common photolithographic patterning technique of lift-off. The procedure consists of the following steps i) the acceptor substrate is patterned using photolithography ii) CVD grown (graphene or MoS2) film is transferred via a polymer assisted transfer from its original substrate to the acceptor substrate iii) then the polymer is dissolved and finally iv) the 2D material is lifted – off by dissolution of the photoresist layer in suitable solvents. The procedure can be repeated for deposition of additional patterned layer to form heterostructures. Furthermore, by employing a double layer photoresist method optimized for the 2D materials, where instead of an alkaline developer solvent is used for the development of the pattern, each sequential transfer / patterning step does not interfere with the already transferred layers, and it is the material agnostic nature of this method that makes it suitable for multilayer stacking of patterned films. References:- [1] K. S. Novoselov,A. K. Geim, S. V. Morozov,D. Jiang,Y. Zhang,S. V. Dubonos, I. V. Grigorieva, A. A. Firsov “Electric Field Effect in Atomically Thin Carbon Films,” Science, vol. 306, no. 5696, pp. 666–669, 2004. [2] K. F. Mak, C. Lee, J. Hone, J. Shan, and T. F. Heinz, “Atomically Thin MoS2 : A New Direct- Gap Semiconductor,” Phys. Rev. Lett., vol. 136805, pp. 2–5, 2010. [3] X. Wang, H. Feng, Y. Wu, and L. Jiao, “Controlled Synthesis of Highly Crystalline MoS2 Flakes by Chemical Vapor Deposition,” J. Am. Chem. Soc, vol. 135, no. 14, pp. 5–8, 2013. [4] C. C. Huang, F. Al-Saab, Y. Wang, J. Y. Ou, J. C. Walker, S. Wang, B. Gholipour, R. E. Simpson, and D. W. Hewak, “Scalable high-mobility MoS2 thin films fabricated by an atmospheric pressure chemical vapor deposition process at ambient temperature,” Nanoscale, vol. 6, no. 21, pp. 12792–12797, 2014. [5] W. S. Mos, Y. Gong, J. Lin, X. Wang, G. Shi, S. Lei, Z. Lin, X. Zou, G. Ye, R. Vajtai, B. I. Yakobson, H. Terrones, M. Terrones, K. Tay, J. Lou, S. T. Pantelides, Z. Liu, W. Zhou, and P. M. Ajayan, “Vertical and in-plane heterostructures from WS2/MoS2 monolayers,” vol. 13, no. September, p. 8, 2014. [6] W. J. Yu, Z. Li, H. Zhou, Y. Chen, Y. Wang, Y. Huang, and X. Duan, “Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters.,” Nat. Mater., vol. 12, no. 3, pp. 246–52, 2013.
Publication Year: 2017
Publication Date: 2017-09-22
Language: en
Type: article
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