Gun Hwan Lee

Properties of ITO Films Deposited on Plastic Substrate by RF Superimposed DC Magnetron Sputtering Method

Tin doped indium oxide (ITO) films were deposited on plastic films by RF superimposed DC magnetron sputtering method using an In2O3 – 10 wt.% SnO2 target without intentionally heating substrates. We have investigated the effects of an RF superimposed DC power system on the electrical, optical, and mechanical properties of the ITO films by using Four-Point Probe, Hall Effect Measurement, UV-Vis-NIR Spectrophotometer, XRD, and Residual Stress Measurement. With increasing the amount of RF power superimposed on DC power, the sputtering discharge voltages of DC power supply were decreased from –290 V to –100 V, i.e., plasma impedance decreased with an increase of the amount of RF power. The resistivity of the samples drastically decreases with increasing RF power, and shows the lowest value of 3.8×10-4 8·cm. Hall effect measurements explain that the increase of carrier mobility is strongly related with the enhancement of the resistivity of ITO films even though there is no difference on its concentration. The RF power superimposed on DC power also reduces the residual stress of the samples up to the stress level of ~ 200 MPa at optimum values of RF power.

Characteristics of IZSO films deposited by a co-sputtering system

In−Zn−Sn−O films were deposited on a polycarbonate (PC) substrate by a magnetron co-sputtering system using two cathodes (DC, RF) without substrate heating. Two types of ITO targets (target A: doped with 5 wt.% SnO2, target B: doped with 10 wt.% SnO2) were used as an In−Sn−O source. The ITO and ZnO targets were sputtered by DC and RF discharges, respectively, and the composition of the In−Zn−Sn−O films was controlled via the power ratio of each cathode. In the case of ITO target A, the lowest resistivity (4.3×10−4 Ωcm) was obtained for the film deposited at the RF power (ZnO) of 55W. In the case of ITO target B, the lowest resistivity (2.9×10−4 Ωcm) of the film was obtained at the RF power (ZnO) of 30W, which was attributed to the increase in carrier density. Hall mobility decreased with increasing carrier density, which could be explained by the increase in ionized impurity scattering.

Effect of Substrate Temperature on Properties of Indium–Tin-Oxide Films Deposited on Poly(ethylene terephthalate) Substrate by DC Magnetron Sputtering

Indium–tin-oxide (ITO) films were successfully deposited on poly(ethylene terephthalate) (PET) substrates at various temperatures by DC magnetron sputtering. The influence of the substrate temperature on the electrical, structural, mechanical and optical properties and surface morphology was investigated. The optimum electrical, optical and mechanical properties were obtained for the films deposited at a substrate temperature of 70 °C, which was attributed to the enhancement of the surface migration of the sputtered atoms arriving at the substrate surface. On the other hand, the average roughness was increased due to the structural change from amorphous to polycrystalline. However, the electrical and mechanical properties of the films were degraded at temperatures higher than 70 °C. This result could be due to the thermal damage incurred by the PET substrate during the sputtering process.

Deposition of ISZO Films on Polymer Substrate Using Two Cathodes

The electrical, optical and mechanical properties were investigated for the In-Sn-Zn-O films deposited using ITO and ZnO targets, without substrate heating. Three types of ITO target, which are 90wt.% In2O3 : 10wt.% SnO2, 93wt.% In2O3 : 7wt.% SnO2, and 95wt.% In2O3 : 5wt.% SnO2, were used. The power of DC cathode equipped ITO target was fixed at 70W and the power of RF cathode equipped ZnO target was changed from 20W to 60W. The lowest resistivity (2.95x10-4 2cm) was obtained for the In-Sn-Zn-O films deposited under DC power of 70W of ITO (93wt.% In2O3 : SnO2 7wt.%) and RF power of 40W of ZnO target. It is confirmed that surface uniformity, electrical property, and mechanical durability were improved by introduction of Zn atom for all the ITO targets.

Mechanical and Electrical Properties of Ga-Doped ZnO Films Deposited on Flexible Substrate by DC Magnetron Sputtering

Ga-doped ZnO films were deposited on polyethylene terephthalate (PET) substrate by dc magnetron sputtering using a high density GZO target (doped with 6.65 wt% Ga2O3) without substrate heating. We investigated electrical, structural, and mechanical properties of GZO films deposited under various total gas pressures (Ptot). GZO films deposited at Ptot of 2.0 Pa showed the lowest resistivity (2.91 x 10-2 7cm), which could be attributed to higher crystallinity of the film. Also, this GZO film showed the lowest change in resistance (8 R/R0 = 0.3) for the dynamic bending test.

Study on Indium Tin Oxide Films Deposited Using Different Conductive ITO Targets by DC Magnetron Sputtering

Indium Tin Oxide (ITO) films were deposited on nonalkali glass substrate by dc magnetron sputtering using high density ITO targets with different conductivitis. Depositions were carried out at total gas pressure (Ptot) of 0.6 Pa, substrate temperature (Ts) of RT, oxygen flow ratio [O2/(O2+Ar)] of 0 ~ 3.0 % and dc power of 100W. High conductivity target showed relatively high stability in electrical property with increasing target erosion ratio. Optimum O2 addition ratio to obtain the lowest resistivity was decreased with increasing target erosion ratio. High conductivity ITO target could lead to decrease in micro-nodule formation on the target surface because of high cooling. The decrease in resistivity was observed for the film annealed at H2 introduction or without O2 addition in vacuum, where could be attributed to increase in carrier density.