Narrow optical gap ferroelectric Bi2ZnTiO6 thin films deposited by RF sputtering

This work reports the deposition of single phase Bi2ZnTiO6 thin films onto Pt/Si-based substrates using the RF-sputtering method and the respective structural, morphological, optical and local ferroelectric characterization. The thin film grows in the polycrystalline form with tetragonal P4mm symmetry identified by X-ray diffraction. The lack of a spatial inversion centre was confirmed by the second harmonic generation. A narrow indirect optical gap of 1.48 eV was measured using optical diffuse reflectance. The ferroelectric domain reversal was further demonstrated through piezo-response force microscopy. This work demonstrates a practical method to fabricate the BZT perovskite phase, without resorting to high pressure and temperature conditions necessary to synthetize the bulk form, with outstanding optical and ferroelectric properties. This work was supported by national funds through the Portuguese Foundation for Science and Technology (FCT/MEC) and COMPETE 2020. when appropriate, co-financed by FEDER under the PT2020 Partnership Agreement: Grants SFRH/BPD/80663/2011 and SFRH/BPD/92896/2013; Projects IFIMUP-IN:Norte-070124-FEDER-000070; CICECO-AIM: POCI-01-0145- FEDER-007679, PTDC/FIS-NAN/0533/2012, UID/CTM/50011/2013, UID/FIS/04650/2013, CERN/FIS/NUC/0004/2015 and NECL: NORTE-01-0145-FEDER-022096 and UID/NAN/50024/2019. Foundation CAPES through the project PNPD-UFAM/Física/1671526 is also acknowledged.