PDF《Piezoelectric-Potential-Controlled》

2008 Vol. 8, No.

11 3973-3977 10.1021/nl802497e CCC: $40.75 ?

2008 American Chemical Society Published on Web 09/30/2008 and thickness of

1 mm) by using a probe station under optical microscopy. Then silver paste was applied at both ends of the ZnO PFW to ?x its two ends tightly on the substrate;

silver paste was also used as the source and drain electrodes. After the silver paste was dried, a thin layer of polydimeth- ylsiloxane (PDMS) was used to package the device. Finally, a ?exible, optically transparent, waterproof and well-pack- aged device was prepared (see Supporting Information, Figure S1). The study of electromechanical properties of the device was carried out in atmosphere at room temperature. The lower inset in Figure

1 shows the measurement setup. One end of the device was af?xed on a sample holder with another end free to be bent. A three-dimensional mechanical ma- nipulation stage with displacement resolution of

1 ?m was used to bend the free end of the device to produce a compressive strain. Meanwhile the I-V characteristics of the device during deformation were measured by a computer- controlled measurement system. As discussed in ref

12 with consideration of the extremely small diameter of the PFW in comparison to the thickness of the PS substrate, and the length of the substrate is much larger than the length of the PFW;

a bending of the PS substrate produces solely a tensile or compressive strain in the PFW depending on its bending direction. Before the electromechanical measurements, we ?rst tested the original I-V characteristic of the device. We found various I-V characteristics for over two hundreds of devices th........