Effect of SiO2 gate insulator on electrical performance of solution processed SnO2-Based thin film phototransistor

SnO2-based TFTs were fabricated by using the sol-gel spin coating method. SnO2 semiconductor films used as active layers were coated on oxidized Si with different SiO2 thicknesses. AFM was used to analyze the surface morphology. The oxidation states of SnO2 film for Sn3d and O1s were determined by XPS. The parameters demonstrating the electrical performance of a transistor such as mobility (μ), threshold voltage (Vth) and sub-threshold swing (SS) have been determined depending on the thickness of the dielectric layer. The thickness of the dielectric layer played an important role in the device's performance. The highest mobility and Ion/off values were obtained as 7.1 cm2/V.s and 6.98x104 for TFT fabricated with a 150 nm thick SiO2 layer. All the TFTs exhibited photosensing behavior at different light intensities and these results are an indicator that the SnO2 TFT can be effectively utilized in visible photo-detecting device applications.