Controllable Growth of Gold Nanowires for Photonics Applications

We propose a one step method for growing high aspect ratio (6-300) gold nanowire (NW) segments from low aspect ratio (AR) gold nanorods by using the dielectrophoresis method between targeted points, copper electrodes in our case, one of which is stationary and the other movable to control the dimensions. The growth is obtained by applying low ac voltages of 0-4 V between the electrodes, unlike any other methods published. The gold nanowire structures are characterized by electron microscopy. This growth technique allows easy isolation from the solution, unlike chemical growth methods, at the single NW level. We have better control over the length and overall AR of the NW and growth of the NW can be stopped once we obtain the size we need, making the method useful for building optical nanocircuits. Wavelength tunability of surface plasmon resonance peaks, by varying the aspect ratio, makes this a promising tool for various optical applications over a wide range of frequencies.