MOS-FET 구조의 MWCNT 가스센서를 이용한 초희박 NOx 가스 검출 특성

Abstract

Carbon nanotubes(CNT) has strength and chemical stability, greatly conductivity characteristics. In particular, MWCNT (multi-walled carbon nanotubes) show rapidly resistance sensitive for changes in the ambient gas, and therefore they are ideal materials to gas sensor. So, we fabricated NOx gas sensors structured MOS-FET using MWCNT (multi-walled carbon nanotubes) material. We investigate the change resistance of NOx gas sensors based on MOS-FET with ultra lean NOx gas concentrations absorption. And NOx gas sensors show sensitivity on the change of gate-source voltage (<TEX>$V_{gs}=0[V]$</TEX> or <TEX>$V_{gs}=3.5[V]$</TEX>). The gas sensors show the increase of sensitivity with increasing the temperature (largest value at <TEX>$40^{\circ}C$</TEX>). On the other hand, the sensitivity of sensors decreased with increasing of NOx gas concentration. In addition, We obtained the adsorption energy(<TEX>$U_a$</TEX>), <TEX>$U_a$</TEX> = 0.06714[eV] at the NOx gas concentration of 8[ppm], <TEX>$U_a$</TEX> = 0.06769[eV] at 16[ppm], <TEX>$U_a$</TEX> = 0.06847[eV] at 24[ppm] and <TEX>$U_a$</TEX> = 0.06842[eV] at 32[ppm], of NOx gas molecules concentration on the MWCNT gas sensors surface with using the Arrhenius plots. As a result, the saturation phenomena is occurred by NOx gas injection of concentration for 32[ppm].