Volatile organic compound gas sensor using a gated lateral bipolar junction transistor

In this paper, we report the fabrication of a gated lateral bipolar junction transistor (LBJT) that is used as a sensor for volatile organic compound (VOC) gases. The proposed sensor was fabricated using a standard 0.35-μm process. The sensor can function as both a metal-oxide-semiconductor field-effect transistor (MOSFET) and a BJT. The floating gate of the sensor was coated with a solvatochromic dye, which exhibits charge-transfer (CT) characteristics, as the sensing membrane of the sensor. The gated LBJT was driven under emitter (source) bias and base current control. Owing to the interaction of the VOC gas with the sensing membrane, the emitter (source) current value changed; this change was detected by using a semiconductor test and analyzer (STA-EL421, ELECS). Results show that our fabricated semiconductor-based gas sensor can be effectively used under normal temperature.