Tuning of temperature dependence of resonance frequency shift of atomically thin mechanical resonators with van der Waals heterojunction

Atomically thin 2-dimensional (2D) mechanical resonators are expected to be highly sensitive force sensor and high performance nano-electro-mechanical systems because of their excellent electrical and mechanical properties. For practical application, the stability of their resonance frequencies against the temperature is very crucial. Here, we demonstrate the manipulation of thermal expansion coefficients (TECs) by making van der Waals heterojunction, graphene and MoS2, which have opposite signs of TECs. The apparent TEC of the 2D heterojunction is greatly suppressed to 1/3 of monolayer graphene without the limitation of tunability of the resonance frequency by application of electrostatic attraction.