Graphene Field-Effect Biosensing Devices with Water Top Gate
Open Access
Author:
Koger, Brandon M
Area of Honors:
Physics
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Jun Zhu, Thesis Supervisor Jun Zhu, Thesis Supervisor Dr. Richard Wallace Robinett, Thesis Honors Advisor
Keywords:
graphene field-effect FET biosensing
Abstract:
In this thesis, we explore the creation of graphene field-effect devices that use a water top gate. While these devices will eventually be used to detect the attachment of biomolecules, the results of these attachments are currently incomplete.
We studied the gate dependence of our devices both under back gate and top gate. We found that our devices had an average base resistance of around 10 kΩ. Under silicon dioxide (SiO2) back gate, our devices appeared highly p-doped, with the Dirac point shifted greater than 40 V toward positive gate voltages. Under a deionized water top gate, we found that the Dirac peak shifted to a much more reasonable value, somewhere between 0 V and 1 V. We found that the ratio of the efficiency of the top gate to that of the back gate ranged from 7 to 20, with an average around 13. From this, we were able to find a range of carrier mobilities for our devices—up to 4000 cm2V-1s-1 for electrons and up to 6000 cm2V-1s-1 for holes.
