Dielectrophoretic manipulation of individual nickel nanowires for electrical transport measurements

Abstract

Nanowires (NW) have received much attention due to their high aspect ratio, shape anisotropy, relatively large surface area and particular electron transport properties. In addition, since NW present low current levels and high sensitivity, they can be used as sensor devices for several applications. One of the major challenges when dealing with transport measurements in NW is to trap them between electrodes, which allow electrical characterization and therefore fabrication of nanowire-based devices. Electrically neutral NW can be deposited by dielectrophoresis (DEP) method, which requires the application of an alternating electric field between electrodes. In this work, properly dispersed Ni nanowires (NiNW) (length = 4 ± 1 μm, diameter = 35 ± 5 nm) were deposited on top of Pt electrodes using the DEP method. The effects of electrodes geometry and electric field frequency on DEP efficiency were evaluated. For optimized DEP parameters, the process efficiency is up to 85%. The deposited NiNW exhibit a Schottky-like current versus voltage behavior due to the high contact resistance between NiNW and electrode. Its reduction down to two orders of magnitude, reaching value less than the NiNW resistance (∼6 kΩ), was achieved by depositing a 10 nm-thick Pt layer over the NW extremities. Therefore, this method presents a selection of adequate electrical DEP parameters and electrode geometry, making it a suitable process of NW deposition and electrical characterization. This can be used for investigation of electrical transport properties of individual NW and fabrication of NW-based devices, like sensors and field effect transistors.