Tackling Polar Response in Oxygen Deficient KTaO3 Thin Films

abstract

Oxygen deficient KTaO3 thin films were grown by RF magnetron sputtering on Si/SiO2/Ti/Pt substrates. Room temperature X-ray diffraction shows that they are under a compressive strain of 2.3%. Leakage current results reveal the presence of a conductive mechanism, following Poole-Frenkel formalism. The existence of a polar response below T-pol approximate to 367 degrees C was ascertained by dielectric, polarization, and depolarization current measurements. A Cole-Cole dipolar relaxation was evidenced which is associated with oxygen vacancies induced dipoles. After annealing the films in an oxygen atmosphere above T-pol, the aforementioned polar response is suppressed, due to significant oxygen vacancies reduction.

keywords

STRONTIUM-TITANATE; SRTIO3; FERROELECTRICITY; DISPERSION; TANTALATE; OXIDE; RAMAN

subject category

Materials Science; Physics

authors

Mota, DA; Romaguera-Barcelay, Y; Tkach, A; de la Cruz, JP; Vilarinho, PM; Tavares, PB; Moreira, JA; Almeida, A

our authors

acknowledgements

This work was supported by Portuguese Foundation for Science and Technology FCT (PTDC/CTM/64805/2006). A. Tkach also acknowledges FCT for financial support (SFRH/BPD/34607/2007). This work was also supported by QREN through Projecto Norte-070124-FEDER-000070 Nanomateriais Multifuncionais.

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