Atomic Layer MoS2-Graphene van der Waals Heterostructure Nanomechanical Resonators

TL;DR

This paper demonstrates the fabrication and characterization of freestanding atomic-layer MoS2-graphene heterostructures that exhibit high-frequency nanomechanical resonances, revealing insights into interlayer interactions and damping effects.

Contribution

It reports the first experimental realization of freestanding atomic-layer heterostructures with nanomechanical resonances, expanding the potential for atomic-scale device applications.

Findings

Resonance frequencies are between those of pure graphene and MoS2 devices.

Q factors are lower than graphene but similar to MoS2, indicating interface damping.

Heterostructures operate in the very high frequency (VHF) band up to ~100 MHz.

Abstract

Heterostructures play significant roles in modern semiconductor devices and micro/nanosystems in a plethora of applications in electronics, optoelectronics, and transducers. While state-of-the-art heterostructures often involve stacks of crystalline epi-layers each down to a few nanometers thick, the intriguing limit would be heterto-atomic-layer structures. Here we report the first experimental demonstration of freestanding van der Waals heterostructures and their functional nanomechanical devices. By stacking single-layer (1L) MoS2 on top of suspended single-, bi-, tri- and four-layer (1L to 4L) graphene sheets, we realize array of MoS2-graphene heterostructures with varying thickness and size. These heterostructures all exhibit robust nanomechanical resonances in the very high frequency (VHF) band (up to ~100 MHz). We observe that fundamental-mode resonance frequencies of the heterostructure devices fall between the values of graphene and MoS2 devices. Quality (Q) factors of heterostructure resonators are lower than those of graphene but comparable to those of MoS2 devices, suggesting interface damping related to interlayer interactions in the van der Waals heterostructures. This study validates suspended atomic layer heterostructures as an effective device platform and opens opportunities for exploiting mechanically coupled effects and interlayer interactions in such devices.