High-Performance Back-Channel-Etch Thin-Film Transistors With Zinc Tin Oxide as Barrier Layer via Spray Coating

Back-channel-etch (BCE) thin-film transistors (TFTs) with the stacked channel of sputtering InZnO (IZO) and spray coating ZnSnO (ZTO) were fabricated. The spray-coated ZTO film shows an ideal surface morphology with technical optimization. The TFT combined with this ZTO film as barrier exhibits superior performance with higher output current, lower threshold voltage, and higher effective electron mobility. Moreover, the short channel effect is less severe with spray-coated ZTO, and the TFTs also demonstrated excellent stability with voltage shift of less than 1.0 V under positive bias temperature stress (PBTS) and negative bias temperature stress (NBTS) with stress time as 7200 s (temperature as 60°). These results indicate that spray-coated ZTO films as a barrier in BCE structure is feasible for the mass production of oxide semiconductor-based TFT backplanes.