Deveplopment of semiconductor humidity sensors

In this thesis, humidity sensors with a focus of titanium dioxide (TiO2) and tin dioxide (SnO2) were developed on flexible (kapton) and unflexible (Al2O3) substrates. Basically, humidity sensors consist of three layers: substrate, electrode and active / sensing layer. The electrodes of the sensors were created with two different techniques: First, two different patterned electrodes were formed by coating Gold (Au) and Platinum (Pt) on 4 x 7 mm2 Al2O3 substrates with vacuum coating techniques, co-spraying and thermal evaporation. Secondly, one of the non-vacuum coating techniques, ink-jet and Silver (Ag) electrodes were processed on kapton substrates with the inkscape program. Spraying method and non-vacuum coating techniques on electrodes processed on Al2O3 substrates; The active layer was dip-coating, doctor blade and ultrasonic bath coating. A sensor was created by immersion on the electrodes drawn on the Kapton substrate. Thus, a humidity sensor was developed with differences in terms of sensing layer and electrode design. The perceived query and optical characters were determined. The base result of the humidity resistance change of ∆R=(R(%70)-R(%40))humidity resistance was evaluated in several different humidity sensing of the developed humidity sensors. The increase in the change in resistance was interpreted as an increase in the sensitivity to the humidity sensor. A 3715kΩ resistance difference was observed in the sensor produced by co-spraying. The difference in resistance between ink-jet printing and flexible humidity sensors, which is one of the non-vacuum coating techniques, was determined as 3800kΩ for TiO2 and 4500kΩ for SnO2. This situation was interpreted as SnO2 material is more sensitive to humidity. Transmitting TiO2 onto the Al2O3 substrate was found to have the highest resistance difference of all sensors of the sensor surrounded by immersion. While the humidity sensor coated with TiO2 with doctor blade methods showed a resistance difference of 1379kΩ, the humidity sensor coated in the ultrasonic bath showed a resistance difference of 120kΩ. It was evaluated that the use of non-vacuum coating methods reduces the production costs of humidity sensors and can provide an advantage for humidity sensor production.