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In this work, we report the influence of ZnSnO channel layer sputtering power in the stability of ZnSnO TFTs under negative gate-bias illumination stress (NBIS). The origin of threshold voltage shift results from combined effect of two factors between the little defect-induced trap densities originated from oxygen vacancies and better channel–insulator interface. The kinetic energy of the ions at a proper rf sputtering power is responsible for less defect-induced trap density and better channel–insulator interface. Therefore, the ZnSnO TFT fabricated at 75 W sputtering power shows a better NBIS stability. In addition, the trap density is extracted by temperature-dependent field-effect measurements and it is consistent with the change of stability under NBIS and thermal stress. [ABSTRACT FROM AUTHOR]

We investigate the stability of thin film transistors incorporating sputtered InZnO as the channel layer under negative bias illumination stress. The transfer characteristic for various active layer thicknesses is shifted toward the negative direction under negative bias illumination stress and the device with thicker channel layer shows a slighter V TH negative shift than another device under negative bias illumination stress. In order to investigate channel layer thickness can have a great effect on the trap density and thus affect the V TH shift caused by charge trapping; we use temperature-dependent field-effect measurements method to accurately calculate their trap density. The results show that thicker InZnO channel layer has fewer DOSs, resulting in the decrease of charge trapping and the decrease of photoexcitation generated electron carrier. So the device with thicker channel layer shows a slighter V TH negative shift than another device under negative bias illumination stress. [ABSTRACT FROM AUTHOR]