Dielectric ceramics/TiO2/single-crystalline silicon nanomembrane heterostructure for high performance flexible thin-film transistors on plastic substrates

摘要

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.