Photoluminescence and Reliability Study of ZnO Cosputtered IGZO Thin-Film Transistors Under Various Ambient Conditions

Abstract

Zinc oxide (ZnO) cosputtered indium-gallium-ZnO (IGZO) and pure IGZO thin films have been deposited at room temperature by dual RF magnetron sputtering and annealed in argon (Ar), nitrogen (N-2), and oxygen (O-2) ambients. The beneficial effect of various annealing environments appears because of a reorganization of the amorphous network with controlling the defect chemistry in the films as systematically investigated by photoluminescence analysis. The various defects, such as zinc vacancy (V-Zn), zinc interstitial (Zn-i), and oxygen vacancy (V-O), were remarkably enhanced in argon, while suppressed in N-2 and O-2 ambients-leading more reliable cosputtered structure than the IGZO to be utilized in thin-film transistors (TFTs) fabrication for transparent electronics. Furthermore, the ZnO cosputtered IGZO TFTs were also fabricated and systematically investigated the impact of various annealing environments on their performance characteristics. The characteristics were improved in N-2 ambient-displaying the field-effect mobility (mu(FE)) of 16.10 cm(2)/Vs, the threshold voltage (V-th) of 1.50 V, the subthreshold swing of 0.21 V/decade, and the negative bias illumination stress shifting of -2.75 V.