Bulletin of the American Physical Society
APS March Meeting 2011
Volume 56, Number 1
Monday–Friday, March 21–25, 2011; Dallas, Texas
Abstract: S1.00177 : Size effect of silicon nanowires on their pH response
Author:
The silicon nanowire is a promising material for the bio-chemical
electronic
sensors because the local change in the surface charge density
can be easily
transduced to the conductivity change of the nanowire due to its
high
surface-to-volume ratio. We investigated the pH-dependent electronic
transport characteristics of FETs comprised of silicon nanowire
channels of
different sizes. Starting from the p-type SOI wafer with the top
silicon
layer of 40 nm thickness, we employed the conventional `top-down'
process to
fabricate the FET devices with various silicon nanowires: 100,
135, 180,
220, 300 nm in width and 2, 5, 10, 20 $\mu $m in length. The
devices were
electrochemically characterized by I$_{D}$-V$_{G}$ measurements
with a
reference electrode as a gate in the phosphate buffer solutions
of a pH
value ranging from 2 to11. The threshold voltages of all devices
were
extracted from the I$_{D}$-V$_{G}$ curves and their relations to
pH were
compared with simulation results based on the
Gouy-Chapman-Stern-Graham
model. A good linear relation between the threshold voltage and
pH was
observed for all devices in the range of 4 $<$ pH $<$11 with a high
sensitivity of 56 mV/pH which is much higher than the bulk
devices and very
close to the Nernst limit. However, the systematic increase of a
threshold
voltage shift as decreasing nanowire's dimension (width and
length) was also
observed and possible origins are discussed within the scope of the
Gouy-Chapman-Stern-Graham model.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2011.MAR.S1.177
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