The Study On The Controllability Of The Aging Effect Of Ferroelectric Random Access Memory

Among these defects,oxygen vacancy is the most common and typical defect in oxides,strongly influencing the stability and reliability of ferroelectric devices.The ferroelectric aging effect?the gradual change of properties with time?is a well-observed phenomenon associated with oxygen vacancies in ferroelectrics.After a long time,the normal single FE hysteresis?P-E?loop of ferroelectrics becomes a double P-E loop.Consequently,Fe RAM will not keep the nonvolatile feature.Thus,the study of modulating such ferroelectric aging effect is an important issue both for the applications the fundamental understanding.We launch a systematic investigation of the ferroelectric aging by tentatively designing a series of experiments on the aging effect of Ba TiO₃ samples doped with different ionic rad ii.O ur experimental results reveal that the doping with small radii ions shows the clear aging effect,while the big radii ion-doping suppresses the aging effect.The suppression is mainly attributed to the kinetically limited migration of oxygen vacancies due to the lattice shrinkage.Thus,according to the actual needs,we can realize the kinetic control of such ferroelectric aging effect through selecting various ions with different radii.Moreover,we study the external field effects on aging phenomeno n of acceptor-doped Ba TiO₃ ceramics.Experimental results demonstrate that all samples show a similar double hysteresis loop under smaller applied electric field,regardless of ionic radius or ionic valence of the acceptor.However,with increasing the app lied electric field,the completely constricted loops gradually start to open,indicating the aging effect becomes weak under larger electric field.The unified microscopic mechanism responsible for the similar aging behavior in different acceptor-doped Ba TiO₃ ceramics may be that the larger field is considered to kinetically facilitate a part of oxygen vacancies short-range hopping.As a result,the defect dipole field provided by oxygen vacancies and the associated defect dipoles frozen in the original states decreases,thus contributing to the weaker aging effect.