An MWCNT-doped SnO_2 thin film NO_2 gas sensor by RF reactive magnetron sputtering

摘要

An MWCNT-doped (multi-walled carbon nanotube) SnO_2 thin film NO_2 gas sensor, prepared by radio frequency reactive magnetron sputtering, showed a high sensitivity to ultra-low concentrations of NO_2 in the parts per billion range. X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy (SEM) characterizations indicated that the MWCNTs were affected by the morphology of the SnO_2 thin film and the particle size. The properties of the MWCNT-doped SnO_2 sensor, such as sensitivity, selectivity, and response-recovery time, were investigated. Experimental results revealed that the MWCNT-doped SnO_2 thin film sensor response to NO_2 gas depended on the operating temperature, NO_2 gas concentration, thermal treatment conditions, film thickness, and so on. The mechanism of the gas-sensing property of the MWCNT-doped SnO_2 thin film sensor was investigated and showed that the improved gas-sensing performance should be attributed to the effects between MWCNTs (p-type) and SnO_2 (n-type) semiconductors.