Frequency and phase noise of ultra-high Q silicon nitride nanomechanical resonators

TL;DR

This paper investigates the amplitude and phase noise characteristics of ultra-high Q silicon nitride nanomechanical resonators, revealing intrinsic frequency fluctuations likely caused by defect motion, and introduces a method to analyze these fluctuations.

Contribution

It provides a detailed measurement and modeling of noise in high-Q nanomechanical resonators, highlighting intrinsic frequency fluctuations and proposing a new analysis technique.

Findings

Amplitude noise aligns with thermomechanical model

Resonators show significant extra phase noise

Frequency fluctuations suggest defect motion with broad relaxation times

Abstract

We describe the measurement and modeling of amplitude noise and phase noise in ultra-high Q nanomechanical resonators made from stoichiometric silicon nitride. With quality factors exceeding 2 million, the resonators' noise performance is studied with high precision. We find that the amplitude noise can be well described by the thermomechanical model, however, the resonators exhibit sizable extra phase noise due to their intrinsic frequency fluctuations. We develop a method to extract the resonator frequency fluctuation of a driven resonator and obtain a noise spectrum with dependence, which could be attributed to defect motion with broadly distributed relaxation times.