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

摘要

A dielectric ceramics/TiO2/single-crystalline silicon nanomembrane (SiNM) heterostructure is designed and fabricated for high performance flexible thin-film transistors (TFTs). Both the dielectric ceramics (Nb2O3-Bi2O3-MgO) and TiO2 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/TiO2 layers to form the heterostructure. The experimental results demonstrate that the room temperature processed heterostructure has high quality because: (1) the Nb2O3-Bi2O3-MgO/TiO2 heterostructure has a high dielectric constant (similar to 76.6) and low leakage current. (2) The TiO2/single-crystalline SiNM structure has a relatively low interface trap density. (3) The band gap of the Nb2O3-Bi2O3-MgO/TiO2 heterostructure is wider than TiO2, which increases the conduction band offset between Si and TiO2, lowering the leakage current. Flexible TFTs have been fabricated with the Nb2O3-Bi2O3-MgO/TiO2/SiNM heterostructure on plastic substrates and show a current on/off ratio over 10(4), threshold voltage of similar to 1.2 V, subthreshold swing (SS) as low as similar to 0.2 V dec(-1), and interface trap density of similar to 10(12) eV(-1) cm(-2). The results indicate that the dielectric ceramics/TiO2/SiNM heterostructure has great potential for high performance TFTs.