We introduce radial encoding of nanowires (NWs), a new method of differentiating and controlling NWs by a small set of mesoscale wires for use in crossbar memories. We describe methods of controlling these NWs and give efficient manufacturing algorithms. These new encoding and decoding methods do not suffer from the misalignment characteristic of flow-aligned NWs. They achieve comparable effective pitch and resulting memory density with axially encoded NWs, while avoiding potential cases of address ambiguity and simplifying NW preparation. We also explore hybrid axial/radial encodings and show that they offer no net benefit over pure codes.

The introduction of an ambient-temperature route for integrating high-mobility semiconductors on flexible substrates could enable the development of novel electronic and photonic devices with the potential to impact a broad spectrum of applications. Here we review our recent studies demonstrating that high-quality single-crystal nanowires (NWs) can be assembled onto flexible plastic substrates under ambient conditions to create FETs and light-emitting diodes. We also show that polymer substrates can be patterned through the use of a room temperature nanoimprint lithography technique for the general fabrication of hundred-nanometer scale features, which can be hierarchically patterned to the millimeter scale and integrated with semiconductor NWs to make high-performance FETs. The key to our approach is the separation of the high-temperature synthesis of single-crystal NWs from room temperature solution-based assembly, thus enabling fabrication of single-crystal devices on virtually any substrate. Silicon NW FETs on plastic substrates display mobilities of 200 cm/sup 2/-V/sup -1/-s/sup -1/, rivaling those of single-crystal silicon and exceeding those of state-of-the-art amorphous silicon and organic transistors currently used for flexible electronics. Furthermore, the generality of this bottom-up assembly approach suggests the integration of diverse nanoscale building blocks on a variety of substrates, potentially enabling far-reaching advances in lightweight display, mobile computing, and information storage applications.