Tuning of the temperature dependence of the resonance frequency shift in atomically thin mechanical resonators with van der Waals heterojunctions

Atomically thin two-dimensional (2D) mechanical resonators should realize highly sensitive force sensors and high performance nano-electro-mechanical systems due to their excellent electrical and mechanical properties. However, practical applications require stability of the resonance frequencies against temperature. Here, we demonstrate the manipulation of the thermal expansion coefficients (TECs) by creating a van der Waals heterojunction using graphene and MoS2, which have opposite signs of TECs. Our method greatly suppresses the apparent TEC of the 2D heterojunction to 1/3 of the monolayer graphene without the detraction of the tunability of the resonance frequency by electrostatic attraction.