We investigated the transfer characteristics and the gate-bias stability of amorphous indium-gallium-zinc oxide thin-film transistors when the channel layer was exposed to hydrogen, oxygen, air, or vacuum at room temperature during measurements. The threshold voltage and the drain current were changed by the ambient atmospheres. The threshold voltage shift (ΔVth) under gate-bias stress was faster in hydrogen than in oxygen and vacuum. It is suggested that hydrogen exposure degrades the gate-bias stress stability due to surface accumulation layer creation. The characteristic trapping times, τ, in H2, O2, air, and vacuum were 5×103, 1.5×104, 2×104, and 6.3×104 s, respectively.

The authors report on transparent thin-film transistors using amorphous indium zinc oxides for an active channel layer and gate-source-drain electrodes fabricated by rf magnetron sputtering at room temperature. The conducting properties of the amorphous indium zinc oxides were controlled by oxygen partial pressures in the sputtering ambient. An amorphous AlOx served as the gate dielectric oxide. Devices were realized that display a threshold voltage of 1.1V and an on/off ratio of ∼106 operated as a n-type enhancement mode with saturation mobility of 0.53cm2∕Vs. The devices showed optical transmittance about 80% in the visible range.

Effects of ferroelectric BaTiO3 particles were investigated on the dielectric behavior of BaTiO3–Ni–polymethyl methacrylate composites fabricated by a two-step mixing and hot-molding method. The percolation power law in the smearing region was employed to explain the experimental results. The composites exhibit the dependence of the dielectric constant, dielectric loss, and percolation threshold on the concentration and particle size of BaTiO3. The results suggest that BaTiO3 particles play an important role in increasing the percolation threshold and the smearing region as well as the dielectric constant of BaTiO3–Ni–polymethyl methacrylate composites.

We investigated copper oxides for use as an active layer of p-channel field-effect thin-film transistors (TFTs). Cu2O thin films deposited at room temperature using rf magnetron sputtering were transformed to a CuO phase after an annealing treatment in air above 200 °C. The optical bandgaps of the Cu2O and CuO were 2.44 and 1.41 eV, respectively. The bottom gate structured TFTs fabricated using CuO active layers operated in a p-type enhancement mode with an on/off ratio of ∼104 and field-effect mobility of 0.4 cm2/V⋅s.

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