Influence of charge accumulation at the grain boundary on the electrical behavior of a ferroelectric field-effect transistor

A phase field method was used to investigate the influence of charge accumulation at the grain boundary on the electrical behavior of a ferroelectric field-effect transistor containing a polycrystalline gate. Both the domain structure and the electrical behavior of the ferroelectric field-effect transistor were found to depend on the coefficient χ, which represents the charge accumulation at the grain boundary. With increasing χ, both the width of the memory window of the capacitance–voltage curves and the on-state source–drain current decreased, while the off-state source–drain current increased. This can be explained in terms of the weakening polarization effect in the grain interior owing to the presence of a built-in electric field caused by the accumulated charge at the grain boundary.