Nanowire Properties via Synthesis

Chemical synthesis may replace conventional lithography for carrying out some of the key steps in the fabrication of nanoscale electronic devices, according to a new study. Charles M. Lieber, Chen Yang, and Zhaohui Zhong of Harvard University have demonstrated a method for incorporating nanometer-sized regions of negative charge-carrying (n-type) dopants in silicon nanowires and for tailoring the number, size, and spacing of those regions along the lengths of the wires (Science 2005, 310, 1304). Nanowires with custom-designed electronic functionality built in at preselected locations may serve as circuit components in future nanoscale electronic devices. The group notes that common synthesis methods can lead to uncontrolled deposition of reactive species on nanowire surfaces, which masks the modulation of electronic properties. To avoid this problem, the group uses a finely controlled heating method and grows the nanowires in an H₂ atmosphere, which inhibits the kinetics of surface deposition relative to nanowire elongation.