We report on a measurement procedure to separate ferroelectric switching current and dielectric displacement current from the leakage current in leaky ferroelectric thin-film capacitor structures. The ac current response is determined for two adjacent frequencies. Taking advantage of the different frequency dependencies of the ferroelectric switching current, dielectric displacement current and ohmic current, the hysteresis loop is calculated without performing a static leakage current measurement, which causes a high dc field stress to the sample. 1 Key material parameters for memory applications are the remnant polarization P R and the coercive voltage V C or the coercive field E C . Since the remnant polarization directly correlates with the amount of charge that can be detected during the read operation of the memory cell, high values are desired for memory applications. The coercive voltage is closely linked with the operating voltage of the storage element. In an ideal system, V C determines the voltage that is needed to switch the polarization inside the ferroelectric thin film. In real materials, the operating voltage might be twice the coercive voltage, since a voltage higher than V C is required to switch the polarization completely and a low interface layer may reduce the field inside the ferroelectric layer.2 Both values can be obtained from the hysteresis curve ͑P -V characteristic͒ of the ferroelectric capacitor. For a loss-free ferroelectric capacitor, the hysteresis loop can be acquired by an integration over the displacement current passing through the capacitor. In contrast, real ferroelectric capacitors show a leakage current in addition that superposes the displacement current and that can affect the shape of the hysteresis curve.3 An integration of the monitored current may then result in a nonphysical increase of remnant polarization and coercive field. Graphical 4 as well as numerical methods 5 have been reported to eliminate the leakage contribution from the current response. A common method is to monitor and to withdraw the static leakage current from the dynamic current measurement.5 Here, the voltage is changed stepwise and the dc current is recorded. This measurement procedure has to be repeated for each data point, whereby the duration of a voltage step mainly depends on the relaxation time of the transient signal response and on the required resolution of the monitored current. A typical duration for a voltage step is in the order of seconds. Depending on the number of data points, several minutes are required to measure the dc I -V characteristic. In some cases, the sample cannot withstand the continuous dc field stress, and the characteristic of the capacitor will change during the static leakage current measurement, e.g., due to resistance degradation. Since this tendency increases with reduced sample thickness, the characterization of ultrathin ferroelectric films is a tough business. In view of the continuous trend to miniaturization, an increase of leakage current originating ...

Direct hysteresis measurements on single submicron structure sizes were performed on epitaxial ferroelectric Pb(Zr,Ti)O3 thin films grown on SrTiO3 with La0.5Sr0.5CoO3 (LSCO) electrodes. The samples were fabricated by focused-ion-beam milling resulting in pad sizes down to 200 nm×200 nm. The influence of parasitic capacitance of the measurement setup was eliminated by applying an enhanced compensation procedure. No size effects were observed in capacitors milled down to 400 nm×400 nm. Thus, a published increase of Pmax1 for decreasing pad size can be explained by the parasitic influence of the setup. Finally, the inaccuracy of increasing coercive voltage due to the coating of the cantilever of the atomic force microscope is discussed.

We report on the integration of fully functional ferroelectric PbTiO3 nanostructures of typically less than 100nm lateral extension into a low-k dielectric hydrogen silsesquioxane film. Chemical mechanical polishing of the dielectric layer down to an overall thickness below the nanoparticles height exposes the structures. After confirmation of the piezoelectricity of individual embedded grains, gold electrode pads are deposited to characterize several of these grains in parallel. Evidence of ferroelectric switching is observed and discussed within an equivalent circuit model. This paves the way to a better integration and statistical analysis of ferroelectric nanostructures.

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Purpose -This paper seeks to analyse the different characteristics a bill of lading holds as a document of title, including the proprietary effects a transfer of goods in transit can have and the bill's use as a means of security as well as its limitations in mo6dern international commerce. Design/methodology/approach -The paper examines the document's nature and the evolution of its traditional legal functions. The analysis includes, among other things, the implications different types of bills have as an instrument in commercial trade. Special attention is given to the attributes that are likely to limit the bill's application in modern international trade, concerning both its scope and value. Finally, the paper offers a set of conclusions and suggests reform measures. Findings -The paper shows how technological innovations in recent years have resulted in the emergence of new forms of transport documentation that might challenge the bill's role in the future. The paper provides a clear understanding of the problems associated with the bill's current form and outlines the main approaches proposed to meet its need for reform. Practical implications -The paper offers a conceptual analysis of the bill's weak points and discusses how simplification and standardisation, a central registry system and electronic transmission of information may be able to increase efficiency. Originality/value -Critical assessment undertaken may pave the way for an open discussion on the subject. Legal culture and mercantile customs should be taken into consideration if a successful and sustainable reform is to be achieved.