Fabrication and modeling of high sensitivity humidity sensors based on doped silicon nanowires

We report a novel method to achieve high-sensitivity capacitive humidity sensors based on silicon nanowires. Silicon nanowires have been grown by means of a vapor-liquid-solid technique. It has been observed that the doping of nanowires leads to a significant improvement in the sensitivity of the device. A circuit model, supported by infrared spectroscopy, is proposed to explain the mechanism of the doping effects on the sensitivity. We have observed that by changing the growth pressure, nanowires with different thicknesses and densities could be achieved. Furthermore, it is demonstrated that nanowires with higher densities result in a constructive effect on the response of the sensor.