Candidate: Mohammad Nouri
Title: Fabrication and Characterization of Molybdenum Disulfide (MoS2) Thin-film Transistors (TFTs)
Date: December 14, 2018
Time: 11:00 AM
Place: QNC 1501
Supervisor(s): Wong, William S.
Abstract:
Molybdenum disulphide (MoS2) is a promising nanomaterials system for developing novel sensors given their large surface-to-volume ratio, carrier mobility, and low defect density surface. Emerging applications in gas detectors may be ideally suited for MoS2-based transistor devices by measuring the current-voltage characteristics of the device as a function of analyte accumulation on the MoS2 surface. In order to realize these potential applications, improved and reproducible fabrication techniques need further development to enable reliable scaling approaches to assemble sensor devices. One approach towards this goal is the implementation of conventional thin-film microfabrication techniques and novel ink-jet printing technologies that may be integrated together for large-scale manufacturing of next-generation sensors. In this research, novel approaches to fabricate thin-film transistors (TFTs) with MoS2 channel is proposed.
Novel transfer techniques will be described to integrate the MoS2 films surface on to a substrate surface through energy modulation of the substrate surface and the MoS2. The thickness of the MoS2 layers will be processed through plasma etching and maskless inkjet fabrication techniques will be used to define electrical contacts to develop a scalable large-area approach to fabricating MoS2-based gas sensors. Electrical contacts in the TFT structure are made of silver nanoparticles that are inkjet-printed. These structures will be fabricated on SiO2/Si wafers to measure the field-effect current-voltage characteristic of the MoS2 transistors.
Preliminary MoS2 TFT characterization indicates that charge trapping is degrading the TFT performance. And potentially hinders the development of the sensors. This research will explore the origin of this defect and minimize its effect on the TFT performance through temperature variable measurements to reveal the density and energy level of the defects within the MoS2 devices.
This project involves cross-disciplinary collaboration in fields of nanotechnology, and electrical device fabrications, creating opportunities to investigate the impact of novel printing approaches employing silver nanoparticles to create MoS2 TFT contacts.
The successful outcome of this research will help provide information for the use MoS2 TFTs as the electronic readout component of sensor arrays that would pave the way toward further applications as environmental and health monitors.