Positioning of carbon nanotubes using soft-lithography for electronics applications

Carbon nanotubes (CNTs) devices have been fabricated using two similar microfabrication processes involving poly(dimethylsiloxane) (PDMS) molecular stamping of 2-thiolpyridine and subsequent self-assembly of CNTs. The two methods allow the fabrication of CNT devices with >90% yield. From Vg=−5to+5V, when Ti–Au electrodes are fabricated on top of the self-assembled CNT films, our devices exhibit p-type field-dependent behavior. When the CNTs have been self-assembled across pre-defined Ti–Au electrodes, metallic conduction has been observed. The electronic properties of our back-gated CNT devices are found to depend upon CNT concentration in the original self-assembly solution. The final structure of the CNT device can affect the field dependency as a result of screening effects at the contact regions, with the 2-thiolpyridine acting as a further screening region.