Electrical characterization of Ba(Zr 0.1Ti 0.9)O 3 thin films grown by pulsed laser ablation technique

Abstract

In situ annealed thin films of ferroelectric Ba(Zr 0.1Ti 0.9)O 3 were deposited on platinum substrates by pulsed laser ablation technique. The as grown films were polycrystalline in nature without the evidence of any secondary phases. The polarization hysteresis loop confirmed the ferroelectricity, which was also cross-checked with the capacitance–voltage characteristics. The remnant polarization was about 5.9 μC cm −2 at room temperature and the coercive field was 45 kV. There was a slight asymmetry in the hysteresis for different polarities, which was thought to be due to the work function differences of different electrodes. The dielectric constant was about 452 and was found to exhibit low frequency dispersion that increased with frequency. This was related to the space-charge polarization. The complex impedance was plotted and this exhibited a semicircular trace, and indicated an equivalent parallel R– C circuit within the sample. This was attributed to the grain response. The DC leakage current–voltage plot was consistent with the space-charge limited conduction theory, but showed some deviation, which was explained by assuming a Poole–Frenkel type conduction to be superimposed on to the usual space-charge controlled current.