Photo-effects on Current Transport in Back-gate Graphene Field-effect Transistor

Graphene, which has attracted wide attention because of its two-dimensional structure and high carrier mobility, is a promising candidate for potential application in optics and electronics. In this dissertation, the photonic effects on current transport in back-gate graphene field-effect transistor is investigated. Chemical vapor deposition (CVD) on metal provides a promising way for large area, controllability and high quality graphene film. The transfer and back-gate transistor fabrication processes are proposed in this dissertation. The theoretical analysis of photodetector based on back-gate graphene field-effect transistor has been done. It is shown that the photo-electronic current consists of current contributions from photovoltaic, photo-thermoelectric and photo-bolometric effects. A maximum external responsivity close to 0.0009A/W is achieved at 30μW laser power source and 633nm wavelength. The photodiode based on graphene/silicon Schottky barrier is also. A computed 238.8 W-1 photocurrent to dark current ratio normalized by the power source (633nm wavelength and 10mW laser) is obtained. An equivalent circuit model of the graphene/silicon Schottky barrier diode compatible with SPICE simulation is developed and simulated photo-response characteristics are presented using analog behavior modeling which are in close agreement with the theoretical analysis. Besides the optical applications, graphene based-transistors can also be used in applications related to space electronics. The irradiation effects including oxide trap charge and graphene layer traps charges are investigated. A semi-empirical model of graphene back-gate transistors before and after irradiation is predicted.