Search

Photovoltaic responses, including photovoltage, photocurrent, illuminated J-V curve, and light-to-electricity power conversion efficiency, were investigated in chemical-solution-derived polycrystalline and epitaxial (Pb0.97La0.03)(Zr0.52Ti0.48)O3 (PLZT) thin films sandwiched between different metal and oxide electrodes. The epitaxial PLZT films with Au/PLZT/Nb-doped SrTiO3 structure exhibited about one order of magnitude larger photocurrent and efficiency over the randomly oriented polycrystalline PLZT films with Au/PLZT/Pt structure due to the high crystalline quality with the reduced defects and enhanced depolarization field. The illuminated J-V curve was approximately linear for both polycrystalline and epitaxial PLZT thin films. The nonzero photovoltaic outputs in the unpoled films were induced by asymmetric interfacial Schottky barriers. The illuminated J-V curve shifted toward the positive voltage direction after positive poling and toward the negative voltage direction after negative poling, and the enhancement of efficiency only occurred when the polarization direction accorded with the direction of Schottky barrier difference at the two electrode interfaces. Thickness dependences of photovoltage, photocurrent, and light-to-electricity conversion efficiency were also examined. It was observed that photovoltage linearly increased with film thickness while both photocurrent and efficiency exponentially increased with the decrease in thickness. Furthermore, at a fixed small film thickness, efficiency was also found to increase reciprocally with the decrease of incident UV intensity. [ABSTRACT FROM AUTHOR]

Ferroelectric (Pb0.97,La0.03)(Zr0.52,Ti0.48)O3 thin films in different thicknesses were fabricated on Pt/Ti/SiO2/Si substrates through a sol-gel process. Film thickness dependence of photoinduced current was investigated under the illumination of ultraviolet light. A theoretical model was developed to describe the thickness-dependent photocurrent. Both the theoretical model and experimental results showed that the photocurrent increases exponentially with the decrease in film thickness. However, photocurrent may drop in the films with the very small thickness of tens of nanometers and below in which the small size effect of ferroelectricity is considered. This model also reveals the relationship between the photocurrent and the internal electric field or remnant polarization and predicts a small diffusion current in the opposite direction at very low field or polarization region. These results provide useful guides for the design of ferroelectric film photovoltaic devices. [ABSTRACT FROM AUTHOR]

A correction to the article "Thickness effects on photoinduced current in ferroelectric (Pb0.97La0.03)(Zr0.52Ti0.48)O3 thin films," by Meng Qin, Kui Yao, Yung C. Liang, and Santiranjan Shannigrahi in issue 101 (2007) is presented.