Effects of Environmental Water Absorption by Solution-Deposited Al 2 O 3 Gate Dielectrics on Thin Film Transistor Performance and Mobility.

In recent years, many solution-processed oxide transistors have been reported with mobility rivaling or exceeding their vacuum-deposited counterparts. Here, we show that water absorption from the environment by solution-processed dielectric materialsexplains this enhanced mobility. By monitoring the water content of Al2 O3 , ZrO2 , and bilayer dielectric materials, we demonstrate how water absorption by the dielectric affects electrical characteristics in solution-processed metal oxide transistors. These effects, including capacitance-frequency dispersion, counterclockwise hysteresis in transfer curves, and high channel mobility, are elucidated by electron transfer between the gate/channel and trap states within the band gap of the dielectric created by the water.