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Advanced Applications of Nanoelectromechanical Systems


Hung, Peter Shek-Ho (2016) Advanced Applications of Nanoelectromechanical Systems. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9J38QJ3.


Nanoelectromechanical systems (NEMS) have advanced the technologies in a wide spectrum of fields, including nonlinear dynamics, sensors for force detection, mass spectrometry, inertial imaging, calorimetry, and charge sensing. Due to their low power consumption, fast response time, large dynamic range, high quality factor, and low mass, NEMS have achieved unprecedented measurement sensitivity. For optimized system functionalization and design, precise characterization of material properties at the nanoscale is essential. In this thesis, we will discuss three applications of NEMS: mechanical switches, using anharmonic nonlinearity to measure device and material properties, and mass spectrometry and inertial imaging.

The first application of NEMS we discuss is NEMS switches, switches with physical moving parts. Conventional electronics, based largely on silicon transistors, is reaching a physical limit in both size and power consumption. Mechanical switches provide a promising solution to surpass this limit by forcing a jump between the on and off states. Graphene, which is a single sheet of carbon atoms arranged in a hexagonal structure, has high mechanical strength and strong planar bonding, making it an ideal candidate for nanoelectromechanical switches. In addition, graphene is conductive, which decreases resistive heating at the contact area, therefore reducing bonding issues and subsequently reducing degradation. We demonstrate using exfoliated graphene to fabricate suspended graphene NEMS switches with successful switching.

The second application of NEMS we discuss in this thesis is the use of mechanical nonlinearity to measure device and material properties. While the nonlinear dynamics of NEMS have been used previously to investigate the longitudinal speed of sound of materials at nano- and micro-scales, we correct a previously attempted method that employs the anharmonicity of NEMS arising from deflection-dependent stress to interrogate the transport of RF acoustic phonons at nanometer scales. In contrast to existing approaches, this decouples intrinsic material properties, such as longitudinal speed of sound, from properties associated with linear dynamics, such as tension, of the structure. We demonstrate this approach through measurements of the longitudinal speed of sound in several NEMS devices composed of single crystal silicon along different crystal orientations. Good agreement with literature values is reported.

The third application of NEMS we discuss is mass spectrometry and inertial imaging. Currently, only doubly clamped beams and cantilevers have been experimentally demonstrated for mass spectrometry. We extend the one-dimension model for mass spectrometry to a novel method for inertial imaging. We further extend the theory of mass spectrometry and inertial imaging to two dimensions by using a plate geometry. We show that the mode shape is critical in performing NEMS mass spectrometry and inertial imaging, and that the mode shapes in plates deviate from the ideal scenario with isotropic stress. We experiment with various non-ideal conditions to match non-ideal mode shape observed.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:NEMS, Graphene, Silicon on insulator, Aluminum Nitride
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Physics
Awards:Graduate Deans’ Award for Outstanding Community Service, 2016. The Lucy Guernsey Service Award, 2016.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Roukes, Michael Lee
Group:Kavli Nanoscience Institute
Thesis Committee:
  • Roukes, Michael Lee (chair)
  • Painter, Oskar J.
  • Schwab, Keith C.
  • Yeh, Nai-Chang
Defense Date:24 May 2016
Record Number:CaltechTHESIS:05272016-154210811
Persistent URL:
Hung, Peter Shek-Ho0000-0002-9034-5330
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9800
Deposited By: Peter Hung
Deposited On:08 Mar 2017 21:13
Last Modified:04 Oct 2019 00:13

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