Embracing structural nonidealities and asymmetries in two-dimensional nanomechanical resonators.

Abstract

Mechanical exfoliation is a convenient and effective approach to deriving two-dimensional (2D) nanodevices from layered materials; but it is also generally perceived as unpreferred as it often yields devices with structural irregularities and nonidealities. Here we show that such nonidealities can lead to new and engineerable features that should be embraced and exploited. We measure and analyze high frequency nanomechanical resonators based on exfoliated 2D molybdenum disulfide (MoS2) structures, and focus on investigating the effects of structural nonidealities and asymmetries on device characteristics and performance. In high and very high frequency (HF/VHF) vibrating MoS2 devices based on diaphragms of ~2−5 μm in size, structural nonidealities in shape, boundary, and geometric symmetry all appear not to compromise device performance, but lead to robust devices exhibiting new multimode resonances with characteristics that are inaccessible in their ‘ideal’ counterparts. These results reveal that the seemingly irregular and nonideal 2D structures can be exploited and engineered for new designs and functions.