Indium phosphide nanowires as building blocks for nanoscale electronic andoptoelectronic devices

Nanowires and nanotubes carry charge and excitons efficiently, and are ther efore potentially ideal building blocks for nanoscale electronics and optoe lectronics(1,2). Carbon nanotubes have already been exploited in devices su ch as field-effect(3,4) and single-electron (5,6) transistors, but the prac tical utility of nanotube components for building electronic circuits is li mited, as it is not yet possible to selectively grow semiconducting or meta llic nanotubes(7,8). Here we report the assembly of functional nanoscale de vices from indium phosphide nanowires, the electrical properties of which a re controlled by selective doping. Gate-voltage-dependent transport measure ments demonstrate that the nanowires can be predictably synthesized as eith er n- or p-type. These doped nanowires function as nanoscale field-effect t ransistors, and can be assembled into crossed-wire p-n junctions that exhib it rectifying behaviour. Significantly, the p-n junctions emit light strong ly and are perhaps the smallest light-emitting diodes that have yet been ma de. Finally, we show that electric-field-directed assembly can be used to c reate highly integrated device arrays from nanowire building blocks.