Elastic strain engineered nanomechanical GaN resonators with thermoelastic dissipation dilution up to 600 K

Conventionally, mechanical resonators exhibit evident degradation in quality factor and large frequency fluctuation at elevated temperatures above room temperature. Here, we show that the quality factor of up to 10 5 of a highly stressed GaN on Si nanomechanical resonators experiences little change as temperature increasing to 600 K and the temperature coefficient of the resonance frequency (TCF) is as low as several ppm/K, several times lower than those of the conventional GaN mechanical resonators. The high quality factor and low TCF at high temperatures are attributed to the high stress and the geometrical nonlinearity of dynamical strain in the GaN resonator, where the dissipation caused by the change of the material properties with the increasing temperature is compensated by the increased stiffness. This observation violates the universality of thermal energy dissipation in mechanical resonators. The results provide a universal strategy for engineering nanomechanical resonators with ultrahigh sensitivity and ultralow noise.