Gated lateral BJT gas sensor for toluene gas detection under room temperature condition

A room temperature gas sensor for toluene detection using gated lateral bipolar junction transistor (BJT) was reported in this study. The proposed device which matches a metal oxide semiconductor field effect transistor (MOSFET) and a BJT was fabricated in a standard 0.35-μm logic process with one-poly and four-metal structure. Then, the 4-aminophthalimide (4AP) dye as a kind of solvatochromic dye which has the charge-transfer (CT) characteristic was used as the sensing membrane. The 4AP dye was immobilized on the floating gate of the gated lateral BJT using self-assembled monolayer (SAM) method. We set this kind of gated lateral BJT operating in the MOSFET-BJT hybrid mode. The electric current changes of the lateral BJT with respect to toluene gas concentrations were obtained by using semiconductor test & analyzer (STA).