This paper reports on the controlled manipulation of high aspect ratio
ferroelectric microtubes on pre-patterned templates by dielectrophoresis.
Microtubes of ferroelectric lead zirconate titanate (PZT, a chemical formula
of Pb(Zr0.52Ti0.48 )O3) with an outer diameter of 2 ?m, a length of about 30
?m and a wall thickness of 400 nm were prepared by vacuum infiltration method
using macroporous silicon templates. To position and align tubes at designed
places, an alternating electric field was applied to a colloidal suspension
of PZT tubes through lithographically defined microelectrodes. This would
enable creation of a stable electrical connection to individual tubes for
making a testing structure for rapid electrical characterization.
Electric-field assisted assembly experiments demonstrated that the frequency
and magnitude of the applied electric field control dielectrophoretic
long-range forces, and hence spatial movement of the tubes in a non-uniform
electric field. The most efficient biasing for the assembly of tubes across
the electrode gap of 12 ?m was a square wave signal of 5 Vrms and 10 Hz. By
varying the applied frequency in between 1 and 10 Hz, an enhancement in tube
alignment was observed due to possible changes in dielectrophoretic torque.
The results indicate a great potential for utilizing dielectrophoresis in
construction of more complex, hierarchical 3-D device structures using the
PZT 1-D like tubes as the building units.
Size Distribution, Mechanical and Electrical Properties of CuO Nanowires Grown by Modified Thermal Oxidation Methods
