Dielectric ceramics/TiO 2 /single-crystalline silicon nanomembrane heterostructure for high performance flexible thin-film transistors on plastic substrates.

A dielectric ceramics/TiO 2 /single-crystalline silicon nanomembrane (SiNM) heterostructure is designed and fabricated for high performance flexible thin-film transistors (TFTs). Both the dielectric ceramics (Nb 2 O 3 -Bi 2 O 3 -MgO) and TiO 2 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 2 layers to form the heterostructure. The experimental results demonstrate that the room temperature processed heterostructure has high quality because: (1) the Nb 2 O 3 -Bi 2 O 3 -MgO/TiO 2 heterostructure has a high dielectric constant (∼76.6) and low leakage current. (2) The TiO 2 /single-crystalline SiNM structure has a relatively low interface trap density. (3) The band gap of the Nb 2 O 3 -Bi 2 O 3 -MgO/TiO 2 heterostructure is wider than TiO 2 , which increases the conduction band offset between Si and TiO 2 , lowering the leakage current. Flexible TFTs have been fabricated with the Nb 2 O 3 -Bi 2 O 3 -MgO/TiO 2 /SiNM heterostructure on plastic substrates and show a current on/off ratio over 10 4 , threshold voltage of ∼1.2 V, subthreshold swing ( SS ) as low as ∼0.2 V dec -1 , and interface trap density of ∼10 12 eV -1 cm -2 . The results indicate that the dielectric ceramics/TiO 2 /SiNM heterostructure has great potential for high performance TFTs.