Dielectric ceramics/TiO/single-crystalline silicon nanomembrane heterostructure for high performance flexible thin-film transistors on plastic substrates.

A dielectric ceramics/TiO/single-crystalline silicon nanomembrane (SiNM) heterostructure is designed and fabricated for high performance flexible thin-film transistors (TFTs). Both the dielectric ceramics (NbO-BiO-MgO) and TiO are deposited by radio frequency (RF) magnetron sputtering at room temperature, which is compatible with flexible plastic substrates. And the single-crystalline SiNM is transferred and attached to the dielectric ceramics/TiO layers to form the heterostructure. The experimental results demonstrate that the room temperature processed heterostructure has high quality because: (1) the NbO-BiO-MgO/TiO heterostructure has a high dielectric constant (∼76.6) and low leakage current. (2) The TiO/single-crystalline SiNM structure has a relatively low interface trap density. (3) The band gap of the NbO-BiO-MgO/TiO heterostructure is wider than TiO, which increases the conduction band offset between Si and TiO, lowering the leakage current. Flexible TFTs have been fabricated with the NbO-BiO-MgO/TiO/SiNM heterostructure on plastic substrates and show a current on/off ratio over 10, threshold voltage of ∼1.2 V, subthreshold swing () as low as ∼0.2 V dec, and interface trap density of ∼10 eV cm. The results indicate that the dielectric ceramics/TiO/SiNM heterostructure has great potential for high performance TFTs.