Duck-Chool Lee

Orientation effects in chemical solution derived Pb(Zr0.3,Ti0.7)O3 thin films on ferroelectric properties

The solely orientation-related effects on ferroelectric and piezoelectric properties of Pb(Zr0.3,Ti0.7)O3 (PZT) thin films with identical processing conditions were investigated using near lattice matched Pt electrodes, that is, (111)-textured Pt for (111)-oriented PZT thin films and (100)-textured Pt for (100)-oriented films. As a result, the film composition, microstructure, and topography were highly similar in all cases. (111)-oriented tetragonal PZT films exhibited highly rectangular P–V hysteresis loops with a slightly better fatigue endurance than the (100)-oriented films. However, the measured d33 values of (100)-oriented PZT films were somewhat higher than those of (111)-oriented films, indicating a consistency with C–V curves. It was shown that in tetragonal symmetry, the intrinsic effect was largest in the piezoelectricity of PZT thin films.

Quaternary Alloy Films for Thin Film Resistors

In this study, we fabricated the quaternary alloy films of Ni–Cr–Al–Cu for thin film resistors using five different target compositions. Thin films were deposited by a DC/RF magnetron sputter and patterned for the measurement of temperature coefficient of resistance (TCR). The TCR of the Ni–Cr–Al–Cu thin films with composition contents and the effects of annealing in air atmosphere up to 400°C were examined. The TCR decreased as the O2 content decreased in film. We chose 5 mTorr as an optimum pressure. Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis of a thin film with a composition confirmed that the sharp increase in the TCR of films annealed at 400°C in air is due to the formation of the rhombohedral NiO phase in the film. The TCR decreased as the Cr content increased or the impurity (Al, Cu) content increased. Above 38 wt% of Cr, the TCR changed to a negative value. The result of XRD analysis revealed that the decrease in the TCR was due to the presence of microcrystalline microstructures in these thin films. The optimal composition was determined to be 51 wt%Ni–41 wt%Cr–4 wt%Al–4 wt%Cu (target 3) and the optimal annealing condition 250°C/3.5 h in air. We obtained thin film resistors of low TCR under ±10 ppm/°C.

Surface modification of polymer insulator by plasma surface treatment

In this study, composite materials were put to dry interfacial treatment by use of plasma technology. It has been presented that the optimum parameters for the best wettability of the samples at the time of generation of plasma were oxygen atmosphere, 0.1 torr of system pressure, 100 W of discharge power, and 3 minutes of discharge time. The contact angles of the samples treated under the optimum conditions and the samples that had not been treated at all were 78/spl deg/ and 72/spl deg/, respectively.

Composition control and electrical properties of Ni-Cr thin films prepared by co-sputtering method

For thin resistor films with low TCR (temperature coefficient of resistance) and high resistivity, we have prepared the thin films by cosputtering method with pure Ni and Cr targets and studied the effect of the process parameters on the electrical properties. In sputtering process, DC/RF power and pressure are varied as controllable parameters. We have investigated the microstructure and measured the electrical properties. When the Ni/Cr ratios of the deposited thin films were 0.8 /spl sim/ 1.5, the resistivity was 100 /spl sim/ 120 /spl mu/ /spl Omega//spl middot/cm. Below a Ni/Cr ratio of 1.5 (above 40[wt%] of Cr), the TCR became negative. The TCR of the thin films decreased from -30 ppm//spl deg/C to -75 ppm//spl deg/C with increasing Cr content. It is suggested that the composition ratio and electrical properties of thin films can be controlled by variation of sputter process parameters.

The effect of the process parameters on the electrical properties of Ni-Cr-Si alloy thin resistor films

For thin resistor film with low TCR (temperature coefficient of resistance) and high resistivity, we have fabricated thin films using the DC/RF magnetron sputtering of 51 wt%Ni-41 wt%Cr- 8 wt%Si alloy target and studied the effect of the process parameters on the electrical properties. Resistivity was 172 [/spl mu//spl Omega//spl middot/cm] and 209 [/spl mu//spl Omega//spl middot/cm] and TCR were -52 [ppm//spl deg/C] and -25 [ppm//spl deg/C] for RF and DC as a power source, respectively. The sheet resistance and TCR increase with increasing the substrate and annealing temperature. From these results, it is suggested that the sheet resistance and TCR of thin films can be controlled by variation of sputter process parameters and annealing of thin film.

Manufacture of insulating agents for electric field relaxation using functionally graded materials, with electric field calculations

The authors of this paper have previously developed a successive layer accretion method based on vacuum filtration, for the manufacture of functionally graded materials (FGMs) by a progressive lamination procedure. For this, they have been granted a U.S. Patent. Using this method, it is possible to manufacture FGMs with thicknesses ranging from several millimetres to several centimetres. The authors have previously manufactured functionally graded materials consisting of iron (III) oxide-kaolin, copper oxide-kaolin and titanium oxide-kaolin, using the said successive layer accretion method. The manufactured FGMs were examined using an SEM to investigate their grading characteristics. Electrical properties such as resistivity, permittivity and permeability were also measured. In the present paper, they report results of permittivity and resistivity measurements conducted on an FGM consisting of titanium oxide and kaolin.

The dielectric properties of functional PVDF thin films by physical vapor deposition method

PVDF thin films were fabricated by physical vapor deposition (PVD). The effect of incremental increases of applied electric field on the dielectric constant is related to the one directional array molecular structure. The dielectric absorption moves to higher frequencies with increasing specimen temperature, in accordance with Debye theory.

Functional plasma-polymerized thin films prepared by a new type of reactor

A novel gas-flow type reactor for plasma polymerization was developed to synthesize functional polymers which enhance the reaction of radicals activated in the discharge. Styrene was used for the polymerization. The molecular structure and the molecular weight distribution were studied. The polymer was evaluated as an electron beam resist. The sensitivity of the film formed by the new reactor was higher than the reported values and a fine pattern was successfully developed in the resist by a wet process.<<ETX>>

Dielectric and Piezoelectric Properties of Low Temperature Sintering PCW-PMN-PZT Ceramics according to MnO 2 Addition

In this study, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, PCW-PMN-PZT ceramics using LiCO, BiO, and CuO as sintering aids were manufactured according to the amount of MnO addition. Their microstructural, dielectric and piezoelectric properties were investigated. When the sintering aids were added, specimens could be sintered below 95, but mechanical qualify factor decreased. Therefore, MnO was added excessively to the PCW-PMN-PZT ceramics to increase mechanical quality factor. At the sintering temperature of 95, the density, dielectric constant(), electromechanical coupling factor(k), mechanical quality factor(Q) and Curie temperature(T) of 0.1 wt% MnO added specimen showed the optimal values of 7.75 g/㎤, 1503, 0.57, 1502, and 337, respectively, for multilayer piezoelectric transformer application.ation.n.

Effect of CuO on the Low Temperature Sintering Properties of PSN-PNN-PZT Ceramics

In this study, in order to develop the low temperature sintering ceramics for ultrasonic vibrator, Pb(Sb/Nb/) O-Pb(Ni1/3/Nb2/3/)O-Pb(Zr0.48/Ti0.52/)O ceramics were manufactured as a function of the amount of CuO addition, and their dielectric and piezoelectric characteristics were investigated. With increasing CuO addition, the grain size and density increased up to 0.3 wt% CuO addition. Taking into consideration electromechanical coupling factor(kp/) of 0.53, mechanical quality factor(Qm/) of 423, dielectric constant(r/) of 1,759 and piezoelectric constant(d33/) of 362pC/N, it could be concluded that 0.5 wt% CuO added composition ceramic sintered at 920 was suitable for ultrasonic vibrator application.