Abstract:
We performed a feasibility study of tailoring sensitivity of Si nanowire through backgate bias
arrangement for various NW length and thickness. Three different thicknesses of 100 nm, 50 nm
and 25 nm were chosen and each thickness consisted of 5 different channel lengths - 1000 nm,
750 nm, 500 nm, 250 nm and 100 nm respectively. It can be seen that the backgate bias has a big
influence on the sensitivity of a p-type SiNW. A backgate bias leading to a depletion of the NW
body increases the sensitivity whereas the backgate bias leading to an accumulation of
significant carriers decreases the sensitivity of NW. For a fixed NW thickness, a decrease of NW
length found to degrade sub-threshold slope and hence NW sensitivity. But for a fixed NW
length a decrease of NW thickness improves the sub-threshold characteristics and sensitivity.
When the NW thickness is 100 nm a peak sensitivity of 2390%/v is found for 1um long NW
which degrades to a value of 349%/V at 100nm length. However, 100 nm long NW’s sensitivity
can be improved by reducing NW thickness and adjusting backgate bias. A 100 nm long 25 nm
thick NW exhibits an improved sensitivity of 2730%/V with +7V of backgate bias. This result
implies that with appropriate backgate bias arrangement, low doped then NW can be used for
single molecule detection as biosensors. Our simulation revealed that a 25 nm thick 1 um long
NW with +7V of backgate bias gives a sensitivity of 3050 %/V.
Description:
This thesis submitted in partial fulfillment of the requirements for the degree of B.Sc in Electrical and Electronic Engineering of East West University, Dhaka, Bangladesh.