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In this article, we examine the initial polarization of PbTiO3 thin films grown epitaxially on SrRuO3 electrodes. It is found that the as-grown predominant polarization is directed toward the SrRuO3 bottom electrode in films thinner than 20 nm and directed toward the top surface in thicker films. The data is interpreted in terms of a Landau–Ginzburg–Devonshire model for a semiconducting ferroelectric with asymmetric boundary conditions. Based on the measured hysteresis loops and the stability of the two polarization directions with time, it is concluded that charged defects serve to impose a preferential downward polarization in very thin films. [ABSTRACT FROM AUTHOR]

Observation of stripe domains in PbTiO3 thin films using standard x-ray diffraction analysis at room temperature is discussed. High-quality c-axis oriented thin films of varying thickness, from 6 to 210 unit cells, were grown on buffered NH4–HF etched SrTiO3(001) and Nb:SrTiO3(001) substrates using off-axis radio frequency magnetron sputtering. High-resolution linear Qx scans reveal a superstructure around the specular Bragg peaks, consistent with the presence of ferroelectric stripe domains. For thin samples, the stripe width is found to be proportional to the square root of the film thickness, with random in-plane orientation of domains. For films with a thickness of more than ∼100 unit cells, both monodomain samples and stripe domains were observed. We present evidence for the presence of a threshold depolarization field, above which there is a monotonically decreasing relationship between the domain width and the depolarization field. Furthermore, simulations show that random variations in size of the domains affect the separation of the diffuse scattering peaks from that of the specular reflection. [ABSTRACT FROM AUTHOR]

The crystalline and dielectric properties of sputter deposited PbTiO3 thin films were investigated as a function of the film thickness and growth temperature. The crystalline quality was found to be independent of the film thickness from 2.4 to 200 nm. The capacitance of 0.12 mm2 Pt/PbTiO3/SrRuO3 and Pt/PbTiO3/Nb:SrTiO3 capacitors was found to deviate from the ideal parallel plate capacitance for PbTiO3 films thinner than 10 nm. The decrease in capacitance was consistent with field penetration into the electrodes. The surface Pb content, as determined from x-ray photoelectron spectroscopy, was found to decrease with increasing growth temperature from 700 to 760 °C. However, no change could be observed in the crystalline quality. [ABSTRACT FROM AUTHOR]

Epilayer control of photoassisted oxidation and reduction on the ferroelectric PbTiO3 polar surface was investigated. Photo-oxidation of a AgNO3 electrolyte resulting in formation of Ag7NO11 particles was observed on the PbTiO3/Nb:SrTiO3 film surface; whereas PbTiO3/SrRuO3/SrTiO3 leads to AgNO3 reduction under UV illumination. The oxidation reaction resulting in the formation of Ag7NO11 is explained in terms of a rectifying interface between PbTiO3 and Nb:SrTiO3, controlling the charge transport during UV photocatalysis. [ABSTRACT FROM AUTHOR]

In this study, we rely on low-angle annular dark-field scanning transmission electron microscopy to probe the interface strain profile in epitaxial PbTiO3/SrTiO3 thin-films. All samples displayed a compressively strained layer at the PbTiO3/SrTiO3 interface, with the strain vector parallel to the polarization direction. The width of the strained layer was found to be ∼15–30 Å, dependent on the electrode environment. Our findings open a perspective to use interface strain engineering in combination with control of electrostatic boundary conditions as a tool to monitor the effective interface polarization. These findings have implications for future use of ferroelectrics in electronic and mechanical devices. [ABSTRACT FROM AUTHOR]

A correction to the article "Epilayer control of photodeposited materials during UV photocatalysis" is presented.