An Investigation on the Comparative Sensor Performance of Polysilicon Nanowires with Single Crystal Silicon Nanowire

Abstract

We study for the first time the effect of nanowire thickness and doping concentration on the electrical characteristics of single crystal and polycrystalline silicon nanowire biosensors. For nanowire thicknesses of 100 nm and 75 nm, a plausible sub-threshold slope around 100 mV/decade for a viable biosensor operation only achieve if doping concentration is 2×1016/cm3 or below both for single crystal and poly Si nanowires. For a 50nm nanowire thickness a relatively wide doping concentration range with a maximum doping up to 4×1017/cm3 choose for biosensor design while maintaining decent sub-threshold characteristics. The widest range of doping concentrations choose for 25nm and 10nm nanowire thickness with a maximum doping up to 1018/cm3 while maintaining a promising sub-threshold slope around 95 mV/decade for a viable biosensor design using single crystal and polycrystalline silicon nanowires. In general poly Si NW shows inferior characteristics than single crystal Si NW. However, for 10nm Si NW single crystal & poly Si NW show same sub-threshold slopes at all doping densities. Considering the fact that spacer etch process provides the cheapest & mass manufacturable platform for biosensor fabrication using poly Si material in comparison to the available single crystal platforms. It decides from this work that poly Si NW biosensor with Si thickness ≤ 10nm is the possible commercial route of sensor fabrication.