Copper phthalocyanine thin film transistors for hydrogen sulfide detection

Bottom contact organic thin film transistors (OTFTs) using SiO2 dielectric layer deposited on silicon wafer were fabricated for the gas sensor application. Copper phthalocyanine (CuPc) was used as an active layer of OTFT device to test current–voltage characteristics and gas-sensing properties of the device. When the device was exposed to the atmosphere of hydrogen sulfide (H2S) at room temperature, the source–drain current changed within a few minutes at the appropriate gate voltage and drain voltage. The dependence of sensing properties on the thickness of the insulator layer was investigated. The results showed that the device with an insulator layer of 195 nm exhibited the optimum electronic and sensing properties comparing with other devices based on the insulator layer of 125 nm and 300 nm.