Simple chemical solution deposition of Al₂O₃ dielectric layers for low-cost fabrication of transparent electronic devices

This study investigates the influence of chemically synthesized Al₂O₃ dielectric layers on the performance of both metal–insulator-metal (MIM) capacitors (FTO/Al₂O₃/Au) and transparent thin film transistors (TTFTs) (FTO/Al₂O₃/ZnO/Au). Using two distinct formulations, a detail comparison based on varying precursors concentrations and the deposition time is presented. Scanning electron microscopy shows a nanopore morphology in the Al₂O₃ dielectric layers. Electrical characterizations for MIM devices yielded leakage currents around 6×10^-4A∙cm² and capacitance values in the 107–77 nF/cm² range. For TTFTs, drain current vs drain-source voltage (I_D-V_DS) (∼1-8.5μA) and drain current vs gate voltage (I_D-V_GS) (on/off ratio 2.4 × 10²) were measured with chemically synthesized ZnO. Using a zinc oxide semiconductor as the active channel, the threshold voltage (V_on/off = ~ 36 V) and mobility (µ = 1.23 cm²/Vs) was obtained. The application of Al₂O₃ as the dielectric gate, which acts as a substrate for ZnO deposition during device fabrication, induced a ZnO dendritic-like surface morphology, influencing channel conduction and exhibiting distinctive electrical behaviors corresponding to each formulation. Beyond the demonstrated capabilities of Al₂O₃ in these devices, this material demonstrates advantages for highly transparent and effective low-cost device fabrication.