Highly stable Si MOSFET-type humidity sensor with ink-jet printed graphene quantum dots sensing layer

This paper investigates humidity sensing characteristics of a silicon metal oxide semiconductor field effect transistor (Si MOSFET)-based humidity sensor having horizontal floating-gate (FG) interdigitated with controlgate (CG). The sensing material of the humidity sensor is graphene quantum dots (GQDs), deposited locally on the interdigitated CG-FG area by an ink-jet printing method using a small amount of the GQDs solution. The humidity sensing characteristics of the sensor are measured as a parameter of relative humidity (RH). The response of the humidity sensor is 78 % to the humid air of 81.3 % RH. We also adopt a pulsed pre-bias method to improve the response and recovery characteristics of the humidity sensor. The response and recovery characteristics of the sensor can be improved 30 % and 40 % respectively by applying a pre-bias of 2 V and -1 V to the CG. In all relative humidity ranges, the FET-type humidity sensor has highly stable and reproducible characteristics in long-term measurements for 5 months.

Automated summary

The paper explores the humidity sensing characteristics of a silicon metal oxide semiconductor field effect transistor (Si MOSFET)-based humidity sensor using graphene quantum dots (GQDs) as the sensing material. The sensor demonstrates a response rate of 78% to humid air with a relative humidity of 81.3%, and the response and recovery characteristics can be improved significantly by applying a pulsed pre-bias method. The FET-type humidity sensor shows highly stable and reproducible characteristics in long-term measurements over a period of 5 months across all relative humidity ranges.