Nitrogen-doped amorphous oxide semiconductor thin film transistors with double-stacked channel layers

In this study, we combine the amorphous InZnO (a-IZO) films and the nitrogen-doped amorphous InGaZnO (a-IGZO:N) to fabricate the amorphous oxide semiconductor (AOS) thin film transistors (TFTs) with the double-stacked channel layers (DSCL). The a-IZO/a-IGZO:N TFT showed the excellent performance with the field-effect mobility of 49.6 cm2 V−1 s−1 and the subthreshold swing of 0.5 V/dec. More interestingly, very stable properties were observed in the bias stress and light illumination tests for these a-IZO/a-IGZO:N TFTs, as seemed to be the evident improvements over the prior arts. The improved performance and stability might be mainly due to the hetero-junctions in the channel layers and less interface/bulk trap density from the in situ nitrogen doping process in the a-IGZO layers. In addition, the passivation effect of the a-IGZO:N films also made some contributions to the stable properties exhibited in these novel DSCL TFTs.