Sol-gel-derived transparent metal oxide flexible field effect transistors

ZnO and ZnO:Al thin films have been successfully synthesized by simple solution processable method at low temperature. Highly crystalline (002) preferentially oriented, uniform, and smooth ZnO:Al thin films are produced. The electrical, J-V and C-V, measurements revealed higher current flow and more carrier concentration, respectively, for ZnO:Al samples compared with pristine ZnO. ZnO- and ZnO:Al-based field effect transistors (FETs) were fabricated using SiO2 and TiO2 gate dielectric layers onto flexible plastic, ITO and rigid, p-Si substrates. The ZnO:Al-based FETs measured better transistor performance with both SiO2 and TiO2 gate dielectrics as compared with ZnO-based TFTs. The saturated field effect mobilities 5.78 and 4.96 cm2/Vs were measured for ZnO:Al-based TFTs with SiO2 and TiO2 dielectrics, which reasonably higher than 0.51 and 0.43 cm2/Vs, respectively, measured for pristine ZnO TFTs. The effect of smooth surface and reduced grain boundaries of ZnO:Al layer contributed to measure the low-interface trap density and trap density at grain boundaries. The reported procedure can be applicable to produce large area transparent electronics onto flexible plastic substrates.