High-Performance Flexible Single-Crystalline Silicon Nanomembrane Thin-Film Transistors with High‑<i>k</i> Nb₂O₅–Bi₂O₃–MgO Ceramics as Gate Dielectric on a Plastic Substrate

A novel method of fabricating flexible thin-film transistor based on single-crystalline Si nanomembrane (SiNM) with high-<i>k</i> Nb₂O₅–Bi₂O₃–MgO (BMN) ceramic gate dielectric on a plastic substrate is demonstrated in this paper. SiNMs are successfully transferred to a flexible polyethylene terephthalate substrate, which has been plated with indium-tin-oxide (ITO) conductive layer and high-<i>k</i> BMN ceramic gate dielectric layer by room-temperature magnetron sputtering. The BMN ceramic gate dielectric layer demonstrates as high as ∼109 dielectric constant, with only dozens of pA current leakage. The Si–BMN–ITO heterostructure has only ∼nA leakage current at the applied voltage of 3 V. The transistor is shown to work at a high current on/off ratio of above 10⁴, and the threshold voltage is ∼1.3 V, with over 200 cm²/(V s) effective channel electron mobility. Bending tests have been conducted and show that the flexible transistors have good tolerance on mechanical bending strains. These characteristics indicate that the flexible single-crystalline SiNM transistors with BMN ceramics as gate dielectric have great potential for applications in high-performance integrated flexible circuit