Low-Temperature All-Solution-Derived Amorphous Oxide Thin-Film Transistors

We prepared thin-film transistors (TFTs) in which all the layers were fabricated using simple chemical solution-processed, vacuum-free routes, followed by thermal annealing at 400°C. A ruthenium oxide (RuO_2) film prepared via low-temperature processing was used for both gate and source/drain electrodes. Amorphous lanthanum–zirconium oxide (LZO) and zirconium–indium–zinc oxide (ZIZO) films were used as the gate insulator and channel layer, respectively, which enabled the fabrication of a TFT with the desired performance at a sufficiently low temperature. The ultraviolet-ozone (UV/O3) treatment was adopted to channel layer in order to facilitate precursor decomposition and condensation processes. As a result, the obtained “on/off” ratio, sub-threshold swing voltage, and channel mobility were approximately 6 × 10^5, 250 mV/decade, and 5.80 cm^V^s^, respectively. This result contributes to the development of sustainable “completely printed inorganic electronics.

Impact of UV/O_3 treatment on solution-processed amorphous InGaZnO_4 thin-film transistors

Ultraviolet–ozone (UV/O_3) treatment was adopted to the fabrication of solution-processed amorphous In–Ga–Zn–O thin-film transistors (TFTs), with metal composition of In:Ga:Zn = 1:1:1 represented by InGaZnO_4. By applying UV/O_3 treatment In–Ga–Zn–O gel films, their condensation was notably enhanced through decomposition of organic- and hydrogen-based elements, which drastically improved the quality of the amorphous InGaZnO_4 films. As a result, high TFT performance, with values of on/off ratio, 10^8; subthreshold swing, 150 mV/decade; threshold voltage, 9.2 V; and field-effect mobility, 5.1 cm^2 V^ s^, was achieved

Ferroelectric-Gate Thin-Film Transistor Fabricated by Total Solution Deposition Process

We have fabricated inorganic ferroelectric-gate thin film transistors (FGTs) using only a chemical solution deposition (CSD) process. All layers, including the LaNiO_3 (LNO) gate electrode, Pb(Zr,Ti)O_3 (PZT) ferroelectric-gate insulator, indium-tin-oxide (ITO) source/drain electrodes , and ITO channel, were formed on a SrTiO_3 (STO) substrate by the CSD process. We obtained an local epitaxially grown PZT/LNO perovskite hetero-structure with good crystalline quality and no interfacial layer. The fabricated FGT exhibited typical n-channel transistor operation, with a counterclockwise hysteresis loop due to the ferroelectric nature of the PZT-gate insulator, and also exhibited good drain current saturation in output characteristics. These properties are equivalent to or better than those obtained with FGTs fabricated by means of conventional vacuum processes. The obtained on/off current ratio, memory window, and subthreshold voltage swing were about 10^5, 2.5 V, and 357 mV/decade, respectively

Totally solution-processed ferroelectric-gate thin-film transistor

We have fabricated inorganic ferroelectric-gate thin film transistors (FGTs) using only a chemical solution deposition (CSD) process. All layers, including the channel [indium-tin-oxide (ITO)], ferroelectric-gate insulator [Pb(Zr,Ti)O_3], gate electrode (LaNiO_3) and source/drain electrodes (ITO), were formed by the CSD process. The fabricated FGT exhibited typical n-channel transistor operation with good saturation in drain current and drain voltage (I_D-V_D) characteristics. The obtained on/off current ratio, memory window, and subthreshold voltage swing were about 10^7, 2.5 V, and 420 mV/decade, respectively