Fabrication and Characteristics of the Si-Nanowire Based Gas Sensor Using Top-Down Technique

Abstract

The applications of gas sensors become more diverse and the demands for highly sensitive and fast responsive gas sensors have been increased. Silicon nanowire (Si-NW) structure has been studied as a novel gas sensor due to high surface-to-volume ratio, fast response time, low cost, and low power consumption. The Si-NW devices have been fabricated using top-down approach and characterized the performances in detecting hazardous gases. When the Si-NW devices are exposed to gas, the drain current is changed by absorption of the gas molecules on the sensor surfaces. The characteristic of the drain current along the drain voltage showed ideal resistor behaviors in the fabricated devices. For the gas detection, ammonia is chosen which is corrosive, stinking, and harmful to humans, so fast and high sensitive detection should be needed to get rid of it at work place and living environment. The sensitivity increases linearly along with the ammonia concentration, and the detection limit and the sensitivity were 610 ppm and 370%, respectively. The response time was less than 1 min, so fast detection can be conducted. Also, the fabricated Si-NW showed a reproducible response when repeatedly exposed in ammonia gas.