Impact of depolarization electric-field and charge trapping on the coercive voltage of an Si:HfO2-based ferroelectric capacitor

Abstract The shift of coercive voltage ( V c ) during cycling is investigated on ferroelectric (FE) silicon-doped hafnium oxide thin films with different (i) Si concentrations in HfO 2 , (ii) thickness of the ferroelectric layer ( T FE ), and (iii) thickness of the interface layer ( T IL ). We find that the depolarization field ( E dep ) and charge trapping are two major root-causes for the shift of coercive voltage. The increased remanent polarization ( P r ) with cycling of up to 10 5 causes a strong E dep , which leads to a higher voltage for polarization switching. On the other hand, the trapped charge improves the charge compensation, and then it suppresses the V c shift due to E dep : in the case of Si doping content, T FE , and T IL , the difference in the magnitude of V c increases by 4.5%, 0.5% and 3% while the difference in E dep increases by 5%, 8% and 15%, respectively. To investigate the rate of charge trapping, the defect band energy level is extracted by two-state NMP theory incorporated into a ‘Comphy’ tool. These results suggest that the strategy discussed above is a promising approach to designing FE-HfO 2 devices.