Amorphous silicon thin-film transistors and arrays fabricated by jet printing

Phase-change wax-based printed masks, in place of conventional photolithography, were used to fabricate hydrogenated amorphous silicon thin-film transistors (TFTs). Wax-mask features with a minimum feature size of ∼20 μm were achieved using an acoustic-ink-printing process. Both discrete and matrix addressing structured bottom-gate TFTs with source–drain contacts overlapping the channel were created using a four-mask process. The TFTs had current–voltage characteristics comparable to photolithographically patterned devices, with mobility of 0.6–0.9 cm²/V s, threshold voltage of 2–3 V, and on/off ratios exceeding $107$ for devices with channel lengths below 50 μm.