Fabrication of MoS₂-Graphene Heterostructures for Application in High-Speed High-Responsivity Photodetectors

Juan Pablo Campbell Naranjo, Zhuowa Wu, Ryan James Bunyard, James Xu, Jie Goodrich, and Huizhong Xu



Department of Physics & Astronomy, San Francisco State University

1600 Holloway Avenue, San Francisco, CA 94132

Atomically thin 2D transition metal dichalcogenides such as MoS­₂ have shown promise for use in high-efficiency photodetectors (PDs) due to their tunable band gap [1], excellent switching ratio, and high responsivity. For example, PDs based on CVD- grown monolayer MoS₂ and bismuth electrode contacts have demonstrated photoresponsivities of up to 300 A W­^-1 at 400 nm wavelength [2]. However, applications for MoS₂-based PDs are limited as their relatively low carrier mobility results in generally lower speeds. To overcome this limitation, PDs based on van der Waals heterostructures, in particular vertical MoS₂-graphene heterostructures, have gained much attention in recent years [3,4]. In this study, we demonstrate the fabrication of MoS₂-graphene vertical heterostructure photodetectors based on mechanically exfoliated MoS₂ of varying thicknesses. By exploiting the combined advantages of the high photosensitivity of MoS₂, the small Schottky barrier between MoS₂ and graphene [5], and the short carrier transit time of graphene; we hope to lower the photocurrent response time while maintaining high photosensitivity.

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[2] H.-L. Sinn et al., Adv. Photonics Res. 4, 2300029 (2023).[3] N. Flöry et al., Nat. Nanotechnol. 15, 118-124 (2020).

[4] B. Hyot et al. Nanotechnology 35, 165503 (2024).

[5] J.Y. Kwak et al., Nano Lett. 14, 4511 (2014).