A method of sensing gas by a field effect transistor, FET, gas sensor device comprising at least one gate, a source, a drain, a semiconductor channel arranged between the source and the drain, wherein the semiconductor channel and the at least one gate form a FET channel-gate coupling by which a gate potential is arranged to control a current through the semiconductor channel,
- at least one space arranged between the at least one gate and the semiconductor channel, wherein the at least one space is configured to receive the gas,
- and a substrate,
- wherein the FET gas sensor device further comprises at least one layer provided on at least a portion of the semiconductor channel, wherein the at least one layer comprises a first layer comprising metal nanoparticles embedded therein,
- wherein the metal nanoparticles embedded in the first layer are arranged to interact with the gas received in the at least one space, and
- a third layer, wherein the third layer is dielectric and is arranged to passivate a surface of the semiconductor channel, wherein the third layer is provided on at least a portion of the semiconductor channel, and the first layer is arranged directly on at least a portion of the third layer,
- wherein the third layer has a thickness in a range of 0.5 nm-10 nm configured to allow tunnelling of electrons through the third layer between the metal nanoparticles embedded in the first layer and the semiconductor channel,
- wherein the metal nanoparticles are selected for having a reaction with the gas received in the at least one space to form a new phase in the metal nanoparticles, generate interface dipoles between the metal nanoparticles and the third layer, whereby a potential energy of the metal nanoparticles is changed, to allow the tunnelling of electrons through the third layer to generate a current signal in the current flowing through the semiconductor channel, wherein the first layer is directly coupled to the semiconductor channel by the allowed tunnelling of electrons through the third layer,
- wherein the at least one layer comprises a portion provided on a side surface of the semiconductor channel facing the at least one space configured to receive the gas and a gate of the at least one gate,
- wherein the at least one gate, the semiconductor channel, the at least one space configured to receive the gas, at least one of the source and the drain, and the portion of the at least one layer are arranged in a same plane parallel to a surface of the substrate, the method comprising:
- biasing the source and the drain with a first voltage for generating a current flowing through the semiconductor channel,
- biasing the gate with a second voltage and controlling the current flowing through the semiconductor channel via a FET channel-gate coupling formed by the semiconductor and the at least one gate,
- receiving the gas in the at least one space, whereby the gas, received in the at least one space configured to receive the gas is arranged to influence at least one electrical property of the FET channel-gate coupling,
- sensing gas based on the influenced at least one electrical property of the FET channel-gate coupling.