Sub ppm Gas Sensing Using a CNTFET-Based Sensor Array Fabricated Using Different Metals as Electrodes

This paper deals with the fabrication of carbon nanotube field effect transistors (CNTFETs) for gas sensing applications. The aim of this study is to achieve a sort of fingerprinting of a specific, gas by using an array of CNTFET-based sensors. The electronic fingerprinting will be obtained by exploiting the change of the metal electrode work function after gas exposure. This one strictly depends on the metal/gas interaction and consequently influences univocally the transfer characteristics of each transistors. To demonstrate this original concept; we have fabricated different CNTFETs using different, metal contacts: An, Pt and Mo. Using these transistors, we have shown that it specific gash in our case DiMethyl-Methyl-Phosphonate (DMMP, a strain simulant), interacts specifically with each metal: exposure to 0.5 ppm of DMMP reduces the transistor ON current by 10 %, 60 % and 25 % after 5 minutes respectively for Au, PC, Mo-based CNTFETs at V-GS = -25 Volt. We think that this new approach can be applied for highly selective sensing of various gases using ultra.-compact, room temperature and very low power devices.