Bi-directional porous alumina wire templates for nanowire field-effect transistors

Using readily available materials and equipment we are able to sculpture aluminium wires into cylindrical, bi-directional templates for the synthesis and contacting of nanowires as field-effect transistors. The nanowire template is made by partial anodization of the wire perpendicular to its axis as an isolating layer for a gate electrode, vapour deposition of a metal on this layer as a gate, cutting the wire perpendicular to its axis, and finally anodizing the newly exposed area parallel to the wire axis as a template for nanowires. This results in a nanowire template surrounded by a gate electrode that is isolated from the template by the first anodisation layer. The utility of this structure is demonstrated by a ZnO nanowire field-effect transistor. The ZnO was made by electrodeposition of Zn nanowires in the interior nanoporous template during which an anodic pulse was applied to form a layer of ZnO in the middle of the zinc nanowires. The IV and transfer plots indicate that the ZnO is p-type in depletion mode. This 3-D transistor is unique in that it can be totally fabricated in a beaker without the need for costly clean room and lithography facilities. The ease and low cost of this new approach to nanodevices will have the effect of liberating nanoscience for scientists of moderate means. As a result this will open nanoscience to new ideas and more inputs.