Hong-Hsin Huang

Crystal Structure and Dielectric Properties of Radio Frequency Magnetron Sputtered Nanocrystalline SrTiO3 Thin Films

Nanocrystalline SrTiO3 thin films have been successfully deposited by radio frequency (RF) magnetron sputtering. The perovskite phase was obtained for the SrTiO3 thin films deposited on Pt/Ti/SiO2/Si substrates at 500°C. The SrTiO3 thin films deposited at 500°C were composed of granular crystallites with a size of approximately 35 nm and a thickness of 150 nm. The crystallite size increases with increasing film thickness. The dielectric constant of SrTiO3 thin films decreases with decreasing film thickness by changing the temperature, frequency and bias voltage.

Dielectric Properties and Leakage Current Characterization of the Ba(SnxTi1-x)O3 Thin Films Prepared by Radio Frequency Magnetron Sputtering

Ba(SnxTi1-x)O3 (BSxT1-x, 0≤x≤0.15) thin films deposited by rf magnetron sputtering with platinum (Pt) top and silver (Ag) bottom electrodes have been characterized with respect to the dielectric properties and leakage current density as a function of composition and rf power. BSxT1-x thin films are amorphous when deposited at rf powers of 100 and 125 W, 5×10-3 Torr working pressure, an O2/(O2+Ar) ratio of 1/(1+9) and room temperature. The XRD result shows the presence of a single perovskite phase of BaTiO3, operated at a range of rf power increasing from 125 to 175 W. The maximum capacitance of Pt/BSxT1-x/Si/Ag capacitors increases with increasing Sn content. The ferroelectric characteristics of the capacitance–voltage hystersis loop in the BSxT1-x thin films are observed. The leakage current density of the Pt/BS0.15T0.85/Si/Ag capacitors at 100 kV/cm varies from mid 10-6 to about 10-8 A/cm2 with the rf power decreasing from 175 to 125 W. The dominant conduction mechanism of the BS0.15T0.85 thin films has shown to be related to Schottky emission (SE) and Poole–Frenkel (PF) mechanisms. The remnant polarization (Pr) and coercive electric field (Ec) of the above device appear to decrease with increasing Sn content.

Characteristics and Optical Properties of Ni Nanograins Reduced on TiO2 Film

NiO/TiO2 films with various NiO film thicknesses ranging from 10 to 320 nm were deposited on silicon and glass substrates by e-beam evaporation at 200 °C, and then annealed in H2 atmosphere at 500 °C for 1 h in order to reduce the NiO film to Ni grains on the TiO2 film. The structures of titanium oxide, NiO, and Ni/TiO2 were determined by X-ray diffraction (XRD) analysis, and the morphology of the Ni/TiO2 films was observed by scanning probe microscopy. The ultraviolet–visible (UV–vis) transmittance and vis absorption of the Ni/TiO2 films were measured by UV–vis spectrophotometry. The results showed that an amorphous titanium oxide was obtained as deposited at 200 °C and that the structure change to the anatase phase after 500 °C annealing. As deposited, crystalline NiO films with XRD patterns similar to that of powder were obtained; however, diffraction peaks of (111) and (200) Ni appeared after annealing in H2 atmosphere. Ni nanograins, coarsened grains, and films were obtained on the TiO2 films when the NiO film with a thickness from 10 to 320 nm was reduced in H2 atmosphere at 500 °C. The transmittance of the Ni/TiO2 films decreased with an increase in Ni particle size. The vis absorption measurement showed that the peak shifted toward a shorter wavelength with a decrease in Ni particle size.

Growth Characteristics and Properties of Tin-Doped Indium Oxide Thin Films as a Function of Oxygen Pressure When Prepared by E-beam Evaporation

The Indium Tin Oxide (ITO) thin films were prepared by E-beam evaporation at oxygen pressure ranging from 1 × 10−4 to 1 × 10−3 Torr. The structure was analyzed by X-ray diffraction and the grain size was evaluated by Scherrer formula. The resistivity and transmittance were measured by 4-probe method and UV-Visible spectrophotometer, respectively. The crystallinity of ITO films increases with oxygen pressure increasing which also increase the intensity of (440). The grain size of ITO films increased with the oxygen pressure increasing. The resistivity decreased with oxygen pressure increasing, however, the transmittance increased. These results suggested that the deposition parameter of oxygen pressure plays an important role in ITO thin film preparation by E-bean evaporation.