Atomic-scale fatigue mechanism of ferroelectric tunnel junctions.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34818041.
- Also identified by DOI 10.1126/sciadv.abh2716 and PMC identifier 8612688.
- Licence recorded as CC BY-NC.
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Abstract
Ferroelectric tunnel junctions (FTJs) are promising candidates for next-generation memories due to fast read/write speeds and low-power consumptions. Here, we investigate resistance fatigue of FTJs, which is performed on Pt/BaTiO<sub>3</sub>/Nb:SrTiO<sub>3</sub> devices. By direct observations of the 5–unit cell–thick BaTiO<sub>3</sub> barrier with high-angle annular dark-field imaging and electron energy loss spectroscopy, oxygen vacancies are found to aggregate at the Pt/BaTiO<sub>3</sub> interface during repetitive switching, leading to a ferroelectric dead layer preventing domain nucleation and growth. Severe oxygen deficiency also makes BaTiO<sub>3</sub> lattices energetically unfavorable and lastly induces a destruction of local perovskite structure of the barrier. Ferroelectric properties are thus degraded, which reduces barrier contrast between ON and OFF states and smears electroresistance characteristics of Pt/BaTiO<sub>3</sub>/Nb:SrTiO<sub>3</sub> FTJs. These results reveal an atomic-scale fatigue mechanism of ultrathin ferroelectric barriers associated with the aggregation of charged defects, facilitating the design of reliable FTJs and ferroelectric nanoelectronic devices for practical applications.