Scalable fabrication of individual SWNT chem-FETs for gas sensing

Abstract

We present a scalable, Deep-UV (220 nm) photolithography based process for fabricating low-power gas sensors integrating an individual single-walled carbon nanotube (SWNT) as a sensing element. SWNTs grow from defined catalyst (ferritin) islands, and their density is controlled by controlling the catalyst particle density. By designing the electrode dimensions based on the length distribution of SWNTs, a single-SWNT bridging yield of 30% has been achieved. Furthermore, we show that exposure to NO2 at room temperature results in a positive shift of the threshold voltage. A threshold shift of approximately 2 V for 500 ppb of NO2 is observed. The presented process also enables the possibility of fabricating carbon nanotube sensor arrays, as a large number of single-tube devices can be fabricated in each process run.