Electrical Performance of Zinc Oxide Thin Films Transistors

Abstract

The capacitive properties and performance of ZnO (TFT) thin film transistors prepared at 100°C were studied. The ZnO thin films were deposited by rf magnetron sputtering on silicon substrates. The frequency dependence of the conductivity and the capacity of the ZnO thin films was studied in the frequency range from 5 kHz to 13 MHz. Shown that total conductivity increases with frequency and decreases with temperature. This shows that the thermally activated conduction mechanism maintains the correlated barrier of the charge carrier on the localized states as a function of the experimental data. Activation energy is in the range of literature. ZnO-based transistors (TFTs) show non-linearities in both the current voltage and the transfer characteristics which are explained due to the presence of trap states. These traps cause a reversible threshold voltage change as revealed by low frequency capacitance voltage measurements in metal insulating semiconductor (MIS) capacitors. Thermal degradation experiments in heterojunctions confirm the presence of a trap state at 0.32 eV.