The controlled growth of single metallic and conducting polymer nanowires via gate-assisted electrochemical deposition

The fabrication of nanowires with well-controlled lengths and diameters is the basis of the application of one-dimensional nanostructures in more sophisticated electronic and biomolecular device systems. A wide variety of materials, including metals and conducting polymers, have been utilized in nanowire arrays as building blocks for chemical or biomolecular sensors. Thus far, the cheapest and most effective way of nanowire synthesis is electrochemical deposition. In this work, we investigate a new method of electrochemical deposition using two-dimensional electric fields instead of the conventional one-directional electric field between working electrodes. Reproducible fabrication of metallic (palladium) and conducting polymer (polypyrrole) single nanowires with diameters down to 30-50 nm is achieved by application of a vertical gate electric field in addition to the lateral one between the two working electrodes. Diameters and lengths of the nanowires can be easily controlled by varying the dimensions of the nanochannels in which the nanowires are grown. A good ohmic contact between the nanowire and gold electrodes is also obtained, indicating the feasibility of electronic devices based on the single nanowires synthesized via this method. In conjunction with experimental findings of nanowire growth mechanism under two-dimensional electric field, molecular dynamic simulations are employed to further understand the deposition process. This improved electrochemical deposition is applicable for controlled and simple fabrication of a wide range of metallic and conducting polymeric nanowires with small diameters.