Bias dependent non-linear electrical characteristics of poly-silicon nanowire and assessment of biosensing application using liquid gate

We investigate the bias dependent modulation of the electrical characteristics of poly-silicon nanowire and perform a feasibility study of poly-silicon nanowire for biosensing application using liquid gate arrangement. Electrical characteristics of a 100 nm thick and 10 µm long p-type poly-silicon nanowire with a doping density of 1016/cm3 is investigated. For positive drain voltage application nanowire's output characteristics exhibit a non-linear diode like behavior whereas for negative drain voltages output characteristics exhibit a perfect transistor behavior with saturation in the characteristics. While nanowire's output characteristics reveal quite a drastic change with drain bias polarity, the sub-threshold characteristics exhibit excellent behavior for both positive and negative drain bias application with a sub-threshold slope of 102.61 mv/decade implying that poly silicon nanowire is good candidate for bio sensing operation with an achievable sensitivity around 800%. It is also found that for positive drain voltages sub-threshold characteristics shifts with the change in drain bias providing the flexibility of a wide range of liquid gated voltages for physiological activity monitoring. For negative drain voltages sub-threshold characteristics does not shift thereby restricting the applicable liquid gate voltages for sensitive operation of biosensors. As such, this study reveals the applicable bias conditions of a 10 µm long 100 nm thick low doped p-type poly-silicon nanowire biosensors physiological process monitoring and the maximum achievable sensitivity for detection of biomarkers.