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Description:
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Nanostructures are nanometer scale structures (characteristic length less than 100 nm ) such as
nanowires , ultra -small junctions , etc . Since nanostructures are less stable , their characteristic
volume is much smaller compared to defect sizes and their characteristic length is close to
acoustical phonon wavelength . Moreover , because nanostructures include significantly fewer
charge carriers than microscale structures , electronic noise in nanostructures is enhanced
compared to microscale structures . Additionally , in microprocessors , due to the small gate
capacitance and reduced noise margin (due to reduced supply voltage to keep the electrical field
at a reasonable level ) , the electronic noise results in bit errors . On the other hand , the enhanced
noise is useful for advanced sensing applications which are called fluctuation -enhanced sensing .
In this dissertation , we first survey our earlier results about the limitation of noise posed on
specific nano processors . Here , single electron logic is considered for voltage controlled logic
with thermal excitations and generic shot noise is considered for current -controlled logic .
Secondly , we discuss our recent results on the electronic noise in nanoscale sensors for SEnsing
of Phage -Triggered Ion Cascade (SEPTIC , for instant bacterial detection ) and for silicon
nanowires for viral sensing . In the sensing of the phage -triggered ion cascade sensor ,
bacteriophage -infected bacteria release potassium ions and move randomly at the same time ;
therefore , electronic noise (i .e . , stochastic signals ) are generated . As an advanced model , the
electrophoretic effect in the SEPTIC sensor is discussed . In the viral sensor , since the
combination of the analyte and a specific receptor located at the surface of the silicon nanowire
occurs randomly in space and time , a stochastic signal is obtained . A mathematical model for a
pH silicon nanowire nanosensor is developed and the size quantization effect in the nanosensor
is also discussed . The calculation results are in excellent agreement with the experimental results
in the literature . |