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Welcome to the website of Professor Farrokh Ayazi's research group in the School of Electrical and Computer Engineering at the Georgia Institute of Technology. Research in the Integrated MEMS Laboratory relates to the design, analysis, fabrication, and characterization of Micro and Nano Electro-Mechanical Systems (MEMS and NEMS), with a focus on high Q resonators and resonant gyroscopes. High Q resonators have applications in 'mixed-domain microsystems' such as gyroscopes and accelerometers, low jitter clocks, energy harvesters, biochemical sensors for health and environmental monitoring, as well as wireless communications. On the system side, the group specializes on advance interface circuits and architectures for MEMS and Sensors. 

The Integrated MEMS Laboratory (IMEMS) is a unit member of the Center for MEMS and Microsystems Technologies (CMMT) and of the Institute for Electronics and Nanotechnology at Georgia Tech. 

 

 

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Monocrystalline Silicon Carbide Disk Resonators on Phononic Crystals with Ultra-Low Dissipation Bulk Acoustic Wave Modes

B Hamelin, J Yang, A Daruwalla, H Wen, and F Ayazi

Micromechanical resonators with ultra-low energy dissipation are essential for a wide range of applications, such as navigation in GPS-denied environments. Routinely implemented in silicon (Si), their energy dissipation often reaches the quantum limits of Si, which can be surpassed by using materials with lower intrinsic loss. This paper explores dissipation limits in 4H monocrystalline silicon carbide-on-insulator (4H-SiCOI) mechanical resonators fabricated at wafer-level, and reports on ultra-high quality-factors (Q) in gyroscopic-mode disk resonators. The SiC disk resonators are anchored upon an acoustically-engineered Si substrate containing a phononic crystal which suppresses anchor loss and promises QANCHOR near 1 Billion by design. Operating deep in the adiabatic regime, the bulk acoustic wave (BAW) modes of solid SiC disks are mostly free of bulk thermoelastic damping. Capacitively-transduced SiC BAW disk resonators consistently display gyroscopic m = 3 modes with Q-factors above 2 Million (M) at 6.29 MHz, limited by surface TED due to microscale roughness along the disk sidewalls. The surface TED limit is revealed by optical measurements on a SiC disk, with nanoscale smooth sidewalls, exhibiting Q = 18 M at 5.3 MHz, corresponding to f · Q = 9 · 1013 Hz, a 5-fold improvement over the Akhiezer limit of Si. Our results pave the path for integrated SiC resonators and resonant gyroscopes with Q-factors beyond the reach of Si.

Scientific Reports 9, Article number: 18698 (2019)