Impact of multi-domain effect on the effective carrier mobility of ferroelectric field-effect transistor

HfO2-based ferroelectric field-effect transistors (FeFETs) are a promising candidate for multilevel memory manipulation and brain-like computing due to the multi-domain properties of the HfO2 FE films based polycrystalline structure. Although there have been many reports on the working mechanism of the HfO2-based FeFET and improving its reliability, the impact of multi-domain effect on the effective carrier mobility (mu(channel)) has not been carried out yet. The effective mu(channel) determines the level of readout current and affects the accuracy of the precision of peripheral circuit. In this work, FeFETs with HfZrO x FE gate dielectric were fabricated, and the effect of write (or erase) pulses with linear gradient variation on the effective mu( channel) was studied. For the multiple downward polarization under write pulses, the mu (channel) degrades as the domains gradually switch to downward. This is mainly due to the enhancement of the scattering effect induced by the positive charges (e.g. oxygen vacancies V-O(2+) ) trapping and the increase of channel carrier density. For the erase pulses, the mu( channel) increases as the domains gradually reverse to upward, which is mainly due to the reduction of the scattering effect induced by the detrapping of positive charges and the decrease of channel carrier density. In addition, the modulation effect of multilevel polarization states on mu( channel) is verified by numerical simulation. This effect provides a new idea and solution for the development of low power HfO2-based FeFETs in neuromorphic computing.