High Frequency Thermally Actuated Single Crystalline Silicon Micromechanical Resonators with Piezoresistive Readout

<p>Over the past decades there has been a great deal of research on developing high frequency micromechanical resonators. As the two most common and conventional MEMS resonators, piezoelectric and electrostatic resonators have been at the center of attention despite having some drawbacks. Piezoelectric resonators provide low impedances that make them compatible with other low impedance electronic components, however they have low quality factors and complicated fabrication processes. In case of electrostatic resonators, they have higher quality factors but the need for smaller transductions gaps complicates their fabrication process and causes squeezed film damping in Air. In addition, the operation of both these resonators deteriorates at higher frequencies.</p> <p>In this presented research, thermally actuated resonators with piezoresistive readout have been developed. It has been shown that not only do such resonators require a simple fabrication process, but also their performance improves at higher frequencies by scaling down all the dimensions of the structure. In addition, due to the internal thermo-electro-mechanical interactions, these active resonators can turn some of the consumed electronic power back into the mechanical structure and compensate for the mechanical losses. Therefore, such resonators can provide self-Q-enhancement and self-sustained-oscillation without the need for any electronic circuitry. In this research these facts have been shown both experimentally and theoretically. In addition, in order to further simplify the fabrication process of such structures, a new controlled batch fabrication method for fabricating silicon nanowires has been developed. This unique fabrication process has been utilized to fabricate high frequency, low power thermal-piezoresistive resonators. Finally, a new thermal-piezoresistive resonant structure has been developed that can operate inside liquid. This resonant structure can be utilized as an ultra sensitive biomedical mass sensor.</p>

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Year dc:date.available

2011

Author dc:creator

• Rahafrooz, Amir

Contributors dc:contributor

• Siavash Pourkamali Anaraki, Ph.D.
• Corinne Lengsfeld
• Mohammad Matin
• James Wilson

• Frequency
• Microelectromechanical system resonator
• MEMS
• Piezoresistive readout
• Self-oscillation
• Self-q-enhancement
• Thermal actuation
• Thermal modeling
• Engineering
• Materials Science and Engineering
• Mechanical Engineering

Statement dc:rights

• <p>Copyright is held by the author. User is responsible for all copyright compliance.</p>

Language dc:language

en

Repository record dc:identifier

https://digitalcommons.du.edu/etd/536

OAI identifier oai:identifier

oai:digitalcommons.du.edu:etd-1535