Ching Fang Tseng

Effect of Annealing Temperature on Electrical Properties of ZnTe Layers Grown by Thermal Evaporation

The electrical properties of evaporated ZnTe films were investigated with emphasis on the effects of an annealing temperature from 600oC to 800oC by RTA technique. Crystallinity, carrier concentration, sheet resistance, and mobility are shown to be dependent on the annealing temperature. The highest carrier concentration and lowest sheet resistance are 7.9×1015 cm-3 and 9300 Ω/□ at an annealing temperature of 700oC, respectively. The mobility was found to vary from 20 to 50 cm2V-1S-1. The ZnTe thin films using thermal evaporation can find applications in solar cell or light emitting diodes

Electrical Characteristics of ZnTe Thermoelectric Thin Films

Thermal coating growth of ZnTe thermoelectric films were deposited on n-type Si substrate is studied. Structural analysis through x-ray diffraction (XRD) and scanning electron microscopy (SEM) were sensitive to the RTA treatment. The electrical properties and microstructure of these films were investigated with special emphasis on the effects of various annealing temperatures from 600°C to 800°C by RTA technique. The highest carrier concentration, lowest resistivity and mobility at an annealing temperature of 700°C are 3.5×1015 cm-3, 0.25 Ω-cm, and 49 cm2V-1S-1. The resultant electrical properties have made ZnTe films as very interesting materials for thermoelectric device applications.

Dielectric Characteristics of (Ca0.2Sr0.8)3(ZrxTi1-x)2O7 Ceramics at Microwave Frequencies

(Ca0.2Sr0.8)3(ZrxTi1-x)2O7 (x = 0.02-0.1) ceramic prepared by the solid state method was investigated for its microstructure and microwave dielectric properties. The correlation between the microstructure and microwave dielectric properties was also investigated. By increasing x from 0.01 to 0.06, the dielectric constant and Q×f value of the specimen could be increased from 72 to a maximum of 74, and from 11000 GHz to a maximum of 18000 GHz, respectively. The εr value of 74, the Q×f value of 18,000 GHz, and the τf value of 418 ppm/oC were obtained for (Ca0.2Sr0.8)3(Zr0.06Ti0.94)2O7 ceramics sintering at 1520oC for 4h, and (Ca0.2Sr0.8)3(ZrxTi1-x)2O7 (x = 0.02-0.1) is proposed as a suitable material candidate for application in microwave ceramic temperature sensing antenna.

Structure and Characteristics of ZrO2 Dielectric Thin Films by Sol-Gel Technique

Dielectric properties and microstructures of ZrO2 thin films prepared by the sol-gel method at different annealing temperatures have been investigated. All films exhibited ZrO2 (111) highly orientation perpendicular to the substrate surface and the grain size increased with increasing annealing temperature. Dielectric properties of the Ag/ZrO2/Ag/Si structure were measured by using HP 4192 Impedance Analyzer and Agilent 4155 Semiconductor Parameter Analyzer. The dependence of the microstructure and dielectric characteristics on annealing temperature was also investigated.

Microstructural and Electrical Properties of ZnO Ceramics with ZnO-Na2O-P2O5 Glass Oxide Additions

The compositions, electrical properties and microstructures of zinc oxide ceramics with various 46.6ZnO-20Na2O-33.4P2O5 glass oxide additions prepared by solid-state method have been investigated. The structure of the materials is studied using X-Ray diffraction, and the microstructure is analyzed using scanning electron microscopy. The results indicated that the electrical properties were associated with the amount of 46.6ZnO-20Na2O-33.4P2O5 glass oxide additions and the sintering temperatures. The correlation between the microstructures, oxide additions and the sintering temperature was also discussed. From the results of electrical properties measurements, zinc oxide ceramics with various 46.6ZnO-20Na2O-33.4P2O5 glass oxide additions exhibits a good electrical behavior, which can be a suitable candidate material for electronic device applications.

Investigation of Chelating Agents on Structural and Optical Properties of Mg(Zr0.05Ti0.95)O3 Thin Film on ITO/Glass Substrate

Optical properties and microstructures of Mg(Zr0.05Ti0.95)O3 thin films prepared by sol-gel method on ITO/glass substrates at different amount of chelating agents and annealing temperatures have been investigated. The relative intensity ratio values of the peak Mg(Zr0.05Ti0.95)O3 thin films, secondary phase of MgTi2O5 and grain growth were depended on the amount of chelating agents and annealing temperature. In the optical transmission spectra, the Mg(Zr0.05Ti0.95)O3 thin films present high transparency (over 60%) in the visible region of the spectrum. The dependence of the optical properties and microstructure characteristics on thermal treatment was also investigated.

Influence of Deposition Temperature of ZnTe Films on Silicon by Thermal Evaporation

The microstructure and electrical properties of ZnTe films were investigated by using thermal evaporation with emphasis on the effects of a deposition temperature. Microstructure, crystallinity, carrier concentration, resistivity, and mobility are shown to be dependent on the deposition temperature. The highest carrier concentration of 9.1×1014 cm-3, the lowest resistivity of 9.9 Ω-cm and the largest mobility of 667 cm2V-1S-1 are presented at a deposition temperature of 580oC, respectively. The ZnTe thin films using thermal evaporation can find applications in solar cell or light emitting diodes.

An Easily Realizable Band-Notched UWB Antenna

An easily realizable ultrawideband (UWB) monopole antenna, with band-notched characteristics, is presented. The antenna consists of a circular metal radiation patch, fed by a 50-Ω microstrip transmission line and a rectangular ground plane with a notch cut into it. By etching a modified U-shaped slot in the radiating patch and by properly tuning its location and form, band-rejected filtering properties can be achieved easily in WiMAX/WLAN bands. It has good omni-directional radiation patterns in H-plane and a good agreement between simulation and measurement.

Effect of Annealing Treatments on the Physical Characteristics of (Ca0.8Sr0.2)TiO3 Thin Films by Sol-Gel Method

This paper describes physical properties of (Ca0.8Sr0.2)TiO3 were deposited by sol-gel method with a fix per-heating temperature of 400oC for 60 min at various annealing temperatures from 600oC to 700oC for 60 min. Particular attention will be paid to the effects of an annealing treatment in air ambient on the physical properties. The annealed films were characterized using X-ray diffraction (XRD). The surface morphologies of annealed film were examined by atomic force microscopy and scanning electron microscopy.

Dielectric Properties of Sol-Gel Derived MgAl2O4 Thin Films

This paper describes microstructure characteristics of MgAl2O4 thin films were deposited by sol-gel method with various preheating temperatures and annealing temperatures. Particular attention will be paid to the effects of a thermal treatment in air ambient on the physical properties. The annealed films were characterized using X-ray diffraction. The surface morphologies of treatment film were examined by scanning electron microscopy and atomic force microscopy. At a preheating temperature of 300oC and an annealing temperature of 700oC, the MgAl2O4 films with 9 μm thickness possess a dielectric constant of 9 at 1 kHz and a dissipation factor of 0.18 at 1 kHz.