Centre for Mechanical Technology and Automation, Universidade de Aveiro, Aveiro, Portugal.
Nanotechnology. 2010 Jun 11;21(23):235703. doi: 10.1088/0957-4484/21/23/235703. Epub 2010 May 13.
Zinc oxide (ZnO) thin films were grown on uncoated and zinc-coated Corning glass substrates by pulsed-laser deposition (PLD). X-ray diffraction measurements revealed that the as-deposited films are polycrystalline having preferential orientation along the [0002] and [[Formula: see text]] directions. Transmittance spectroscopy verified that the as-deposited films are transparent with a direct bandgap of about 3.28 eV at room temperature. Piezoresponse imaging and local hysteresis loop acquisition were performed to characterize the piezoelectric and possible ferroelectric properties of the films. The out-of-plane (effective longitudinal, d(parellel)) and in-plane (effective shear, d(perpendicular)) coefficients were estimated from the local piezoresponse based on the comparison with LiNbO(3) single crystals. Measurements of all three components of piezoresponse (one longitudinal and two shear signals) allowed constructing piezoelectric maps for polycrystalline ZnO and to relate the variation of piezoelectric properties to the crystallographic and grain structure of the films. A shifted piezoresponse hysteresis loop under high voltages hints at the possible pseudoferroelectricity, as discussed recently by Tagantsev (2008 Appl. Phys. Lett. 93 202905).
氧化锌 (ZnO) 薄膜通过脉冲激光沉积 (PLD) 在未镀膜和镀锌康宁玻璃衬底上生长。X 射线衍射测量表明,沉积的薄膜是多晶的,具有沿 [0002] 和 [[Formula: see text]] 方向的择优取向。透过率光谱证实,沉积的薄膜在室温下具有约 3.28 eV 的直接带隙,是透明的。压电力成像和局部滞后环采集用于表征薄膜的压电和可能的铁电性能。基于与 LiNbO(3) 单晶体的比较,从局部压电力估计出面外 (有效纵向,d(parellel)) 和平面内 (有效剪切,d(perpendicular)) 系数。压电力的所有三个分量 (一个纵向和两个剪切信号) 的测量允许构建多晶 ZnO 的压电图,并将压电性能的变化与薄膜的晶体学和晶粒结构联系起来。在高电压下滞后环的偏移暗示了可能的准铁电性,正如 Tagantsev (2008 Appl. Phys. Lett. 93 202905) 最近讨论的那样。