Candidate: Gyu Chull Han
Title: Modeling and Simulation of Molybdenum Diselenide (MoSe2) Phototransistors
Date: July 26, 2018
Time: 2:00 pm
Place: EIT 3142
Supervisor(s): Yoon, Young Ki
Abstract:
Since the first demonstration of graphene, two-dimensional (2D) materials have attracted gigantic attentions from the electronic devices community. Transition metal dichalcogenides (TMDs) is one of the 2D materials having semiconducting properties in the form of a transition metal atom (e.g., Mo, W) sandwiched by two chalcogenide atoms (e.g., S, Te, Se). Due to their intriguing electronic and optical properties, TMD devices have been investigated for various applications such as field-effect transistors (FETs), photodetectors, and chemical/biosensors. In particular, TMD phototransistors exhibit high photoresponsivity and specific detectivity, demonstrating their potential for future wearable devices and health monitoring systems.
In this study, the molybdenum diselenide (MoSe2) phototransistor is investigated in terms of theoretical models and numerical simulations. First, models for optical behaviors of MoSe2 phototransistors under illumination have been developed considering two key mechanisms: photoconductive effect for the conductivity increase and photogating effect for threshold voltage shift under illumination. Second, the models for metal/MoSe2 contact and optical behaviors of MoSe2 phototransistors are studied by atomistic quantum transport simulations using the non-equilibrium Green’s function (NEGF) method. Finally, a possible future work will be suggested, which can include the effect of contact resistance at the metal/MoSe2 junction on the photogating effect.