Thermo-mechanical coupling and size effects in micro and nano resonators

Sandeep Kumar,Tarek Alam,Aman Haque

doi:10.1186/2213-9621-1-2

Abstract

Existing models for thermoelastic damping consider geometric size effects only, the focus of this study is on tuning of thermoelastic damping with mechanical strain, which reduces both relaxation rate and thermal conductivity at the nanoscale. We developed a model that accounts for the contribution of tensile force and thermal conductivity in a clamped-clamped configuration nano-resonator. Experimentally measured thermal conductivity is then coupled with the model suggests the existence of a critical length scale (inversion point) below which quality factor increases with increase in thickness and vice versa. The nanoscale strain-thermal conductivity coupling is found to be most effective at and around this inversion point.

Highlights

The ever continuing pursuit for high-precision and low power consumption micro and nano electro-mechanical systems (MEMS and NEMS) actuators, sensors and mechanical filter applications has resulted in increasing attention on resonators used in these devices [1]
Quality factor (Q-factor) is one of the critical performance parameters for resonators, which is influenced by various kinds of energy loss mechanisms and majority of the micro/nano resonator research is devoted on the size and design effects to understand or suppress such mechanisms
We measured the thermal conductivity of 50 nm thick freestanding silicon nitride thin films as a function of mechanical strain, so that this coupling can be used in the theoretical model developed earlier

Summary

Introduction

The ever continuing pursuit for high-precision and low power consumption micro and nano electro-mechanical systems (MEMS and NEMS) actuators, sensors and mechanical filter applications has resulted in increasing attention on resonators used in these devices [1]. Thermoelastic damping, resulting from heat generation due to vibration and dissipation from thermal diffusion, is identified as the fundamental limit for the attainable quality factor of a micromechanical resonator [6]. This is because the literature has only insights on the basic processes of thermo-elastic damping, but there is no effective theory that is capable of reducing the loss around the

Methods

Results

Conclusion