Highly reliable bipolar resistive switching in sol-gel derived lanthanum-doped PbTiO3 thin film: Coupling with ferroelectricity?

Nanoscale PbxLa1−xTi1−x/4O3 (PLT) thin film has been fabricated on Pt\Ti\SiO2\Si substrates by chemical solution deposition (CSD) method. Ferroelectricity of the fresh-made PLT thin film has been clearly detected through piezoelectric force microscopy (PFM) by writing reversible ferroelectric domains. However, PLT thin film also shows off-standard ferroelectric hysteresis loops highly dependent on frequency, indicating large amount of mobile space charges in the film. Subsequent current-voltage (C-V) studies show that sandwich-like Pt\PLT\Pt structure exhibits notable bipolar resistive switching (BRS) characteristics with high stability (> 103 switching cycles). It is found that the C-V curves of both high- and low-resistance states have the feature of space-charge-limited current (SCLC) conduction, indicating important roles of defects in the conduction. X-ray photoelectron spectroscopy measurement further verifies that oxygen vacancies based conductive filament mechanism is likely responsible for the observed RS effect. Our demonstration of stable RS effect in the PLT thin film and its possible coupling with ferroelectricity is promising in device development and applications, such as development of ferroelectric-tunable RS memories.