Fully solution-induced high performance indium oxide thin film transistors with ZrO_x high-k gate dielectrics

Abstract

Solution based deposition has been recently considered as a viable option for low-cost flexible electronics.

Application of ultrasonic sprayed zirconium oxide dielectric in zinc tin oxide-based thin film transistor

“…The reduction in the E g value with the deposition temperature can be attributed to many reasons, including microstructural changes within the film, the presence of localised defects within the ZrO x band structure thereby causing a reduction in the E g value, and the disordered nature of the amorphous materials. 3,8,17 Nevertheless, the E g values being generally high above 5 eV is a good indication that the spray-deposited ZrO x dielectric film would provide enough barrier needed to prevent carrier conduction between the active layer and the gate dielectric layer of TFT.…”

“…During the reverse gate voltage sweeping, these states remain filled until the trapped electrons were thermally de-trapped. 3 Moreover, D it is very important for device stability and charge carrier mobility, which was estimated to be 5.7 Â 10 12 cm À2 for the ZTO/ZrO x TFT. These results show that we obtained a good interface between the ZrO x gate dielectric and the ZTO channel layer.…”

“…Recently metal oxide thin films have attracted significant interest for future electronic applications especially in thin film transistors (TFTs) due to their large-area uniformity, high mobility, good optical transparency in the visible light region, thermal stability, and excellent environmental impact, and they can be produced at low cost. [1][2][3][4][5] However, most of these metal oxide transistors are incorporated into traditional silicon dioxide (SiO 2 ) dielectrics and they are operated at a high voltage window above 30 V, which hinder their use in low-voltage, smart and portable applications. Since the induced electric field directly corresponds to charge accumulation, replacing the SiO 2 gate dielectric layer of TFTs with a high permittivity (high-k) material would help accomplish low operation voltage.…”

“…Among the inorganic high-k dielectrics, zirconium oxide (ZrO x ) is a desirable gate insulator because bulk ZrO 2 has a high permittivity value (B25), low leakage current, good thermal stability, adequate band alignment and forms good adhesion with Si-substrates. 3,15 Most importantly, the wide bandgap (5.0-7.8 eV) of ZrO x is beneficial to suppress charge penetration from the gate electrode and to reduce the generation of charge as a result of the thermal/ photoexcitation process. 8 In the past, good quality ZrO x thin films have been deposited using different methods, for example, atomic layer deposition, sputtering, chemical vapour deposition, and e-beam evaporation, 16 but these methods are very expensive and the growth rate of the thin film is time consuming due to the high vacuum.…”

“…Also, several solution-processed ZrO x dielectric TFTs have been reported via spin coating. 3,25,26,33 In this work, we demonstrate a combination of ultrasonic spray pyrolysis (USP) and spin coating in the fabrication of highquality ZrO x gate dielectrics and ZTO semiconductor, respectively, onto a rigid substrate. To the best of our knowledge, this is the first report of an all-amorphous oxide TFT with low operational voltage.…”