Heterojunction Channel Engineering in Performance Enhancement of Solution-Processed Oxide Thin-Film Transistors

With the continuous development of next generation display techniques, more and more attention has been put on solution-processed oxide thin-film transistors (TFTs). Here, we report the solution-based growth of InZnO/AlInZnO (IZO/AIZO) heterojunction channel layers and their implementation in high-performance TFTs. It is found that the heterojunction transistors exhibit a band-like electron transport, with both current ON/OFF ratio and mobility values significantly higher than single-layer IZO and AIZO devices by more than one order of magnitude. The marked improvement here is demonstrated to originate from the presence of confined free electrons at the atomically sharp heterointerface induced by the large conduction band offset between IZO and AIZO. Further channel engineering including the modification of In:Zn ratios, IZO, and AIZO thicknesses allows us to obtain highperformance heterojunction oxide TFTs with a high current ON/OFF ratio of >5 x 107, a mobility of 14.4 +/- 1 cm(2)/Vs, a turn on voltage close to zero-volt, and a superb stability against bias stresses and long-term storage. The high performance combined with the solution-processability enables the great potential of our reported TFTs in next-generation printable electronics.