The deposition of indium zinc oxide (IZO) thin films was carried out on substrate at room temperature by RF magnetron sputtering. The effects of substrate temperature, RF power and deposition pressure were investigated with respect to physical and optical properties of films such as deposition rate, electrical properties, structure, and transmittance. As the RF power increases, the resistivity gradually decreases, and the transmittance slightly decreases. For the variation of deposition pressure, the resistivity greatly increases, and the transmittance is decreased with increasing deposition pressure. As a result, it was demonstrated that an IZO film with the resistivity of 3.89 × 10^-4 Ω·cm, the hole mobility of 51.28 ㎠/Vs, and the light transmittance of 86.89% in the visible spectrum at room temperature can be prepared without post-deposition annealing.

We investigated a solution-driven Yttrium Tin Oxide (YSnO) film that was imprinted using a parallel nanostructure as a liquid crystal (LC) alignment layer. The imprinting process was conducted at the annealing temperature of 100℃. To evaluate the effect of this process, we conducted surface analyses including atomic force microscopy (AFM). During imprinting, the surface roughness was reduced, and anisotropic characteristics were observed. Planar LC alignment was observed at a pretilt angle of 0.22° on YSnO film. Surface anisotropy induced by imprinting method forces LC to align along the direction of the parallel nanostructure, which is an alternative to conventional polyimide treated using a rubbing process.

In this work, we investigate the effects of lithium doping on the electric performance of solution-processed n-type zinc tin oxide (ZTO)/p-type silicon carbide (SiC) heterojunction diode structures. The proper amount of lithium doping not only affects the carrier concentration and interface quality but also influences the temperature sensitivity of the series resistance and activation energy. We confirmed that the device characteristics vary with lithium doping at concentrations of 0, 10, and 20 wt%. In particular, the highest rectification ratio of 1.89×107 and the lowest trap density of 4.829×1,022 cm^-2 were observed at 20 wt% of lithium doping. Devices at this doping level showed the best characteristics. As the temperature was increased, the series resistance value decreased. Additionally, the activation energy was observed to change with respect to the component acting on the trap. We have demonstrated that lithium doping is an effective way to obtain a higher performance ZTO-based diode.

In this paper, we have studied about the optimum fabrication condition of the printed Indium Tin Oxide (ITO) layers for the electrical resistance-type sensor application. We have investigated on the substrates surface treatments, mixing ratio of organic binder/ITO powder, and viscosity of the printing paste to determine the optimum condition of the screen printed ITO layer. Also, we found that the printing condition is closely related with the sensor performance. To know the feasibility of printed ITO layer as an electrical resistance-type sensor, we have fabricated the ITO sensors with a printed and sputtered ITO layers. The printed ITO films revealed 102 times higher sensitivity than the sputtered ITO layer. Also, the sputtered ITO layer exhibited an operating temperature of 127℃ at the operating voltage of 5 V. While, in case of the printed ITO layer showed the operating temperature of 27.6℃ in high operating voltage of 30 V. We found that the printed ITO layer is suitable for the various sensor applications.

We investigated the effects of annealing on the electrical and thermal properties of ZTO/4H-SiC heterojunction diodes. A ZTO thin film layer was grown on p-type 4H-SiC substrate by using solution process. The ZTO/SiC heterojunction structures annealed at 500℃ show that Ion/Ioff increases from ~5.13×107 to ~1.11×109 owing to the increased electron concentration of ZTO layer as confirmed by capacitance-voltage characteristics. In addition, the electrical characterization of ZTO/SiC heterojunction has been carried out in the temperature range of 300∼500 K. When the measurement temperature increased from 300 K to 500 K, the reverse current variation of annealed device is higher than as-grown device, which is related to barrier height in the ZTO/SiC interface. It is shown that annealing process is possible to control the electrical characteristics of ZTO/SiC heterojunction diode.

Zinc tin oxide transparent thin film transistors (ZTO TTFTs) were fabricated by using n`` Si wafers as gate electrodes. Indium (In), aluminum (Al), indium tin oxide (ITO), silver (Ag), and gold (Au) were employed for source and drain electrodes, and the mobility and the threshold voltage of ZTO TTFTs were observed as a function of electrode. The ZTO TTFTs adopting In as electrodes showed the highest mobility and the lowest threshold voltage. It was shown that Ag and Au are not suitable for the electrodes of ZTO TTFTs. As the results of this study, it is considered that the interface properties of electrode/ZTO are more influential in the properties of ZTO TTFTs than the conductivity of electrode.

Zinc tin oxide transparent thin film transistors (ZTO TTFTs) were fabricated on oxidized n+ Si wafers. The thickness of 30 nm Al2O3 films were deposited on the oxidized Si wafers by atomic layer deposition, which acted as the gate insulators of ZTO TTFTs. The Al2O3 films were rapid-annealed at 400 , 600 , 800 , and 1,000 , respectively. Active layers of ZTO films were deposited on the Al2O3/SiO2 coated n+ Si wafers by rf magnetron sputtering. Mobility and threshold voltage were measured as a function of the rapid-annealing temperature. X-ray photoelectron spectroscopy (XPS) were carried out to observe the chemical bindings of Al2O3 films. The annealing effects of gate-insulator on the properties of TTFTs were analyzed based on the results of XPS.

Transparent thin film transistors were fabricated on n+-Si wafers coated by Al2O3/SiO2. Zinctin oxide (ZTO) films deposited by rf magnetron sputtering were employed for active layers. The mobility(μs), threshold voltage (VT), and sub threshold swing (SS) dependances on ZTO thickness were analyzed. The VT decreased with increasing ZTO thickness. The μs raised from 5.1 cm2/Vsec to 27.0 cm2/Vsec byincreasing ZTO thickness from 7 nm to 12 nm, and then decreased with ZTO thickness above 12 nm. The SS was proportional to ZTO thickness.

Bottom-gate tin oxide (SnO2) thin film transistors (TFTs) were fabricated on N+ Si wafersused as gate electrodes. 60-nm-thick SnO2 thin films acting as active layers were sputtered onSiO2/Al2O3 films. The SiO2/Al2O3 films deposited on the Si wafers were employed for gate dielectrics. Inorder to increase the resistivity of the SnO2 thin films, oxygen mixed with argon was introduced into thechamber during the sputtering. The mobility of SnO2 TFTs was measured as a function of the flow ratioof oxygen to argon (O2/Ar). The mobility variation with O2/Ar was analyzed through studies oncrystallinity, oxygen binding state, optical properties. X-ray diffraction (XRD) and XPS (X-rayphotoelectron spectroscopy) were carried out to observe the crystallinity and oxygen binding state ofSnO2 films. The mobility decreased with increasing O2/Ar. It was found that the decrease of the mobilityis mainly due to the decrease in the polarizability of SnO2 films.

Mg doped zinc tin oxide (ZTOMg) thin films were prepared on glasses by rf magnetron sputtering. O was introduced into the chamber during the sputtering. The optical properties of the films as a function of oxygen flow rate were studied. The crystal structure, elementary properties, and depth profiles of the films were investigated by X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and secondary ion mass spectrometry (SIMS), respectively. Bottom-gate trdnsparent thin film transistors were fabricated on N Si wafers, and the variation of mobility, threshold voltage etc. with the oxygen flow rate were observed.

Transparent thin film transistors (TTFT) were fabricated on N+ Si wafers. SiO2, Si3N4/SiO2 and Al2O3/SiO2 grown on the wafers were used as gate insulators. The rf magnetron sputtered zinc tin oxide (ZTO) films were adopted as active layers. N+Si wafers were wet-oxidized to grow SiO2. Si3N4 and Al2O3 films were deposited on the SiO2 by plasma enhanced chemical vapor deposition (PECVD) and atomic layer deposition (ALD), respectively. The mobility, Ion/Ioff and subthreshold swing (SS) were obtained from the transfer characteristics of TTFTs. The properties of gate insulators were analyzed by comparing the characteristics of TTFTs. The property variation of the ZTO TTFTs with time were observed.