High Frequency readout scheme for Graphene based NEMS

A mechanical system is an excellent choice for studying forces of varying magnitude. The force produces a displacement of the system under study. By measuring this displacement electrically or optically, the force can characterized. In this thesis, the displacement of a nanoelectromechanical system (NEMS) due to thermal energy is of interest. At room temperature, the thermal motion of the system is the smallest amplitude of motion possible and this can be detected if the detector has a high sensitivity. We present a high frequency transmission line resonator operating in the GHz frequency regime as a detector to measure such small changes in motion. Graphene, an atomically thin membrane of carbon will be used in a capacitor geometry with the detector to measure its thermal motion. The motion of graphene is transduced into capacitance which in turn modulates the electrical resonance frequency of the detector. This non-linear effect produces intermodulation sidebands which contain the resonance signature of the graphene membrane which can be read out at thermal noise limited sensitivity. The thesis discusses the design of the detector from analytical modeling to electromagnetic simulations. Fabrication of the complete device is also discussed. Measurement results indicate that the detector has a Q factor of 43 at room temperature. The position and capacitance sensitivity of the detector is estimated to be 0.54 pm/?Hz and 0.58 zF/?Hz respectively at an amplifier noise floor of 1 nV/?Hz .

Subject

graphene
NEMS
microwave
resonator

To reference this document use:

http://resolver.tudelft.nl/uuid:2a160a48-9388-4950-af30-24685f221489

Part of collection

Student theses

Document type

master thesis

Rights

Files

PDF

final_thesis_repository.pdf

13.59 MB

Close viewer