title: Mechanism of polarization fatigue in BiFeO3.
abstract: Fatigue in ferroelectric oxides has been a long lasting research topic since the development of ferroelectric memory in the late 1980s. Over the years, different models have been proposed to explain the fatigue phenomena. However, there is still debate on the roles of oxygen vacancies and injected charges. The main difficulty in the study of fatigue in ferroelectric films is that the conventional vertical sandwich structure prevents direct observation of the microscopic evolution through the film thickness during the electric field cycling. To circumvent this problem, we take advantage of the large in-plane polarization of BiFeO(3) and conduct direct domain and local electrical characterizations using a planar device structure. The combination of piezoresponse force microscopy and scanning kelvin probe microscopy allows us to study the local polarization and space charges simultaneously. It is observed that charged domain walls are formed during the electrical cycling, but they do not cause polarization fatigue. After prolonged cycling, injected charges appear at the electrode/film interfaces, where domains are pinned. When the pinned domains grow across the channel, macroscopic fatigue appears. The role of injected charges in polarization fatigue of BiFeO(3) is clearly demonstrated.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798.
authors.forename: Xi
authors.initials: X
authors.lastname: Zou
authors.forename: Lu
authors.initials: L
authors.lastname: You
authors.forename: Weigang
authors.initials: W
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Ding
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.forename: Tom
authors.initials: T
authors.lastname: Wu
authors.forename: Lang
authors.initials: L
authors.lastname: Chen
authors.forename: Junling
authors.initials: J
authors.lastname: Wang
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D005296:Ferrous Compounds / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D008968:Molecular Conformation; D010316:Particle Size; D012031:Refractometry / Q000379:methods*; D013499:Surface Properties
chemical_list: D005296:Ferrous Compounds; D046911:Macromolecular Substances; C034236:ferrous oxide; D001729:Bismuth