Modeling and simulation of graphene-gated graphene-GaAs Schottky junction field-effect solar cell for its performance enhancement

Modeling and simulation of graphene-gated graphene-GaAs Schottky junction field-effect solar cell is performed using in-house developed algorithm based on finite-difference method, where Poisson and drift-diffusion equations are solved in an appropriate way. Our algorithm is verified by comparing the simulated J-V curve of solar cell with the previous experimental one. The carrier generation rate is calculated with light multireflection in the solar cell excluded, due to large optical absorption coefficient of GaAs, and the radiative recombination in GaAs leads to ~5% light generated carrier loss. The charge transfer effect in graphene is investigated, which can affect open circuit voltage, and in particular for the semiconductor substrate with very low hole mobility. It is further numerically demonstrated that: (1) both open circuit voltage V_OC and short circuit current J_SC of the solar cell are governed by doping concentration through affecting Schottky barrier height and depletion width; (2) the value of V_OC can be effectively adjusted by decreasing the thickness of gate oxide; however, it may result in oxide breakdown or reliability problem; and (3) there is tunability inertia for V_OC with multilayer junction graphene implemented, but it can provide low series resistance.