Search

Epitaxial (PbMg1/3Nb2/3O3)2/3-(PbTiO3)1/3(PMN-PT) films with different out-of-plane orientations were prepared using a CeO2/yttria stabilized ZrO2bilayer buffer and symmetric SrRuO3electrodes on silicon substrates by pulsed laser deposition. The orientation of the SrRuO3bottom electrode, either (110) or (001), was controlled by the deposition conditions and the subsequent PMN-PT layer followed the orientation of the bottom electrode. The ferroelectric, dielectric and piezoelectric properties of the (SrRuO3/PMN-PT/SrRuO3) ferroelectric capacitors exhibit orientation dependence. The properties of the films are explained in terms of a model based on polarization rotation. At low applied fields domain switching dominates the polarization change. The model indicates that polarization rotation is easier in the (110) film, which is ascribed to a smaller effect of the clamping on the shearing of the pseudo-cubic unit cell compared to the (001) case. [ABSTRACT FROM AUTHOR]

In this contribution, we report on the compositional dependence of the mechanical and piezoelectric properties of Pb(ZrxTi1-x)O3 (PZT) thin films fabricated by pulsed laser deposition (PLD). These films grow epitaxially on silicon with a (110) preferred orientation and have excellent piezoelectric properties, which make them outstanding candidates for application in microelectromechanical system devices. Vibrometric measurements on capacitors showed that the effective longitudinal piezoelectric coefficient (d33,f) of 100-nm thick PZT films has a maximum value of 72 pm/V for a composition of x = 0.52. The Young's modulus was determined by measuring the difference in the flexural resonance frequencies of cantilevers before and after the deposition of the PZT thin films. The compositional dependence of the Young's modulus shows an increase in value for the Zr-rich compositions, which is in agreement with the trend observed in their bulk ceramic counterparts. From the obtained dielectric constant and d33,f, we show that the calculated coupling coefficients of the PLD-PZT thin films have higher values for most of the compositions than their ceramic counterparts. [ABSTRACT FROM AUTHOR]

Earlier theoretical reports predicted that the usage of a piezoelectric stressor layer around the FinFET, i.e., the PiezoFET, offers a great potential for steep subthreshold slope devices. For the first time, we analyzed the practical realization of such PiezoFETs comprising a piezoelectric stressor layer, lead–zirconate–titanate (PZT), and aluminum–nitride (AlN) deposited on n-type silicon FinFETs. A high-piezoelectric response in the range of 100 pm/V has been obtained for the PZT PiezoFET evidencing the converse piezoelectric effect in the device. The piezoelectric response for the AlN device was much less (13 pm/V) as expected. Underlying device properties, such as subthreshold swing (SS) and low-field electron mobility have been significantly affected by the presence of the PZT stressor. A 20%–50% change in the mobility and a change in the SS (about 5 mV/decade) have been observed. The change can be attributed to the strain induced reduction of the interface trap density at the Si/SiO2 interface. This strain is partly formed by the bias over the piezoelectric layer, which indicates the converse piezoelectric effect related tunable strain in both the silicon channel and gate oxide. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports the latest experimental results of multilayered, heterolayered, and alternating heterolayered PZT thin films obtained by spin coating on Pt/Ti/SiO2/Si wafers using Zr-rich (P60) and Ti-rich (P40) solutions which were prepared by sol–gel route process. The ferroelectric and piezoelectric properties of the heterolayered and alternating heterolayered P60/P40 thin films were significantly improved when compared to those of multilayered thin films using just P60 or P40 for the same film thickness. The improved properties resulted from the field-induced coupling effect between the rhombohedral (Zr-rich) and tetragonal (Ti-rich) layers which induces domain switching. Namely, the values of the remnant polarization, dielectric constant and piezoelectric coefficient were 18.6 μC cm−2, 1040 and 70 pm V−1 respectively, for alternating heterolayered P60/P40 thin films, while the properties for the purely multilayered P60 and P40 thin films were 14.6 μC cm−2, 860 and 52 pm V−1, and 17.1 μC cm−2, 800 and 50 pm V−1, respectively. The enhancement of the ferroelectric and piezoelectric properties of PZT thin films with increasing film thickness in this case could be explained by the existence of an interfacial layer and substrate clamping. [Copyright &y& Elsevier]