Phase Noise and Frequency Stability of Very-High Frequency Silicon Nanowire Nanomechanical Resonators

Abstract

We report measurements and analyses of noise characteristics of very-high frequency (VHF) silicon nanowire (SiNW) nanoelectromechanical systems (NEMS). VHF SiNW resonators vibrating at ~200MHz typically have displacement sensitivity of ~5fm/(Hz^(1/2)) and force sensitivity of 50~250aN/(Hz^(1/2)) set by thermomechanical fluctuations. They have ~1nm critical amplitude and intrinsic dynamic range of 90~110 dB. Amplifier noise and resistor thermal noise dominate the resonance detection, resulting in in compromised displacement noise floor (typically ≥30 fm/(Hz^(1/2))), dynamic range (reduced to 70~90 dB), and phase noise (≥20~30dB degradation). We develop SiNW-NEMS-based phase-locking techniques to investigate the phase noise and frequency stability performance. Frequency stability of ~0.1ppm and resonant mass sensitivity of ~10 zg (1 zg=10^(-21)g) have been achieved.

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