Sensitivity Tuning of Si Nanowires Through Backgate Bias Arrangement for Biosensing Application

Abstract

We perform a feasibility study of tailoring sensitivity of Si nanowire through backgate bias arrangement for Biosensing application. A 100nm thick and 1μm nanowire with doping concentration of 1016 cm-3 is investigated for different backgate voltages. It is found that backgate bias has significant effect on the sensitivity of p-type Si-NW. Backgate bias for depletion of NW body is found to increase sensitivity of NWs whereas backgate bias for significant carrier accumulation is found to decreases sensitivity of NW. Sensitivity trend of NWs also found to depend on the polarity of drain voltages. When drain voltage is positive, presence of DIBL on the sub-threshold characteristics is found to shift sensitivity curve towards positive top gate voltage with increasing drain voltages. Presence of DIBL on sub-threshold characteristics is somehow found to beneficiary for biosensing application as it provides maximum sensitive operation of Si-NW even without any liquid gating of the top gate. Considering current detection capacities of semiconductor parameter analyzer available in the market a positive drain voltage of 0.9V is found to provide a maximum sensitivity of 2×103%/V even without any liquid gating. Simulation also shows that it is possible to get NWs sensitivity greater than 2×103%/V using liquid gating and providing drain voltages less than 0.5V. When drain voltage is negative no DIBL is observed in the sub-threshold characteristic which mandates liquid gating of the top gate for maximum sensitive operation of Si-NW as biosensor. These results are very significant of p-type Si-NW based biosensors fabricated on SOI platform to ensure maximum sensitive operation for molecular level detection.