Phase detection of water vapor using graphene field-effect transistor

Abstract

We report on the phase-sensitive detection of water vapor using a gas sensor based from a graphene-field effect transistor (GFET). The GFET device was fabricated through photolithography, reactive-ion etching, and electron-beam deposition techniques. Raman spectroscopy confirmed the presence of monolayer graphene across the transistor channel. The GFET gas sensor was used to detect the presence of water vapor in dry air. Alternating current (AC) gas sensing measurements were done by measuring the phase shift between the channel voltage and the gate voltage. The gas sensing measurements showed that the fabricated device can detect a minimum percentage of 50% water vapor concentration in dry air.