Solid State Phenomena Vols. 124-126

Abstract: Processing and properties of a dome-shaped piezoelectric transformer with a composition of 0.03Pb(Sb0.5Nb0.5)O3-0.03Pb(Mn1/3Nb2/3)O3-0.465PbTiO3-0.475PbZrO3 have been investigated. A dome-shaped sample was fabricated by powder injection molding. The dimension of the dome-shaped sample was a 28 mm in diameter and 2.1mm in thickness with a curvature radius of 18 mm. Finite element modeling for the complicated piezoelectric transformer was applied to simulate vibration mode in the sample. The high power characteristics of a dome-shaped piezoelectric transformer were examined by the lighting test for a 55W PL lamp. The 55W PL lamp was successfully driven by the dome-shaped piezoelectric transformer with sustaining efficiency higher than 98%. The transformer with ring/dot area ratio of 2.1 exhibited the maximum properties in terms of output power, efficiency and temperature stability.

Abstract: 0.03Pb(Sb0.5Nb0.5)O3-0.03Pb(Mn1/3Nb2/3)O3-(0.94-x)PbTiO3-xPbZrO3 ceramics doped with CeO2 were synthesized by conventional bulk ceramic processing technique. Phases analysis, microstructures and piezoelectric properties were investigated as a function of CeO2 contents (0.03, 0.05, 0.1 0.3, 0.5 and 0.7wt%). Microstructures and phases information were characterized using a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). Relative dielectric constant (K33 T) and coupling factor (kp) were obtained from the resonance measurement method. Both K33 T and kp were shown to reach to the maximum at 0.1wt% CeO2. In order to evaluate the stability of resonance frequency and effective electromechanical coupling factor (Keff) as a function of CeO2 addition under strong electric field, the variation of resonance and anti-resonance frequency were also measured using a high voltage frequency response analyzer(FRA5096) under various alternating electric fields from 10V/mm to 80V/mm. It was shown that effective electromechanical coupling factor was increased by increasing the CeO2 additions.

Abstract: TiO2 thin films were deposited on both bare Si and Si substrates with ZnO buffer layer (ZnO/Si) by radio frequency (rf) magnetron sputtering of TiO2 target at a substrate temperature of 500
. A mixed gas of Ar and O2 was used for sputtering and O2 flow ratio was changed from 0 to 30%. X-ray diffraction patterns showed that the TiO2 thin films had only rutile structure. The weak diffraction peak from the (110) plane of rutile structure was observed for the TiO2 film formed on bare Si substrate. For the TiO2 film on ZnO/Si, the diffraction peak from the (200) rutile structure was dominant. The diffraction intensity from the rutile structure of TiO2/ZnO/Si was stronger than that of TiO2/Si. This implies that ZnO buffer layer promoted the crystallization of rutile structure.

Abstract: High-quality transparent conductive Al-doped ZnO (AZO) thin films were deposited by pulsed laser deposition on quartz glass substrates at room temperature. We varied the growth condition in terms of oxygen pressure. The structure
and electrical and optical properties of the as-grown AZO films were mainly investigated. The AZO films formed at room temperature showed a low electrical resistivity of 3.01×10-4 ) cm, a carrier concentration of 1.12×1021 cm-3 and a carrier mobility of 18.59 cm2/Vs at an oxygen pressure of 10 mTorr. A visible transmittance of above 83% was obtained. The present results suggest that optimized AZO films should be very useful and effective for flexible display, top emission type of OLEDs and for various other kinds of optoelectronic devices such as flexible solar cell or passive photo device.

Abstract: SnO2 thin films have been grown on Si3N4 substrates and also on Al2O3 sensor substrates with Pt interdigitated electrodes by the pulsed excimer laser deposition (PLD). Palladium doped SnO2 thin film was also prepared by the PLD method combined with the DC sputtering process. The substrate temperature and the oxygen gas pressure were changed from 300 to 500°C and from 100 to 300 mTorr, respectively during deposition. The morphology and structural properties of the prepared thin films have been studied by AFM and XRD. The gas sensing properties of the SnO2 sensor to NO gas was evaluated by measuring electrical resistance between interdigitated electrodes. The highest sensitivity of the undoped SnO2 and Pd doped sensor was found to be around 9.5 and 42, respectively.

Abstract: A preplated frame (PPF) consisting of Au/Pd/Cu-Sn/Cu substrate, i.e., preplated with a Cu-Sn alloy instead of Ni commercially used, was fabricated by electroplating and then the feasibility of the frame as an alternative PPF was investigated. The wettability of the Cu-Sn alloy was better than that of Ni, resulting in excellent contact with the substrate and smoother surface on the upper Au/Pd protective layer. By XPS analyses, it was confirmed that Cu atoms in the Cu-Sn alloy layer did not diffuse through the thin protective layer to the surface at temperatures used in IC assembly. The wire pull-strength and solderability of the Cu-Sn alloy PPF were almost equivalent to those of the Ni PPF. However, the former showed much better corrosion resistance than the latter.

Abstract: Ion shower doping with a main ion source of P2Hx using a source gas mixture of PH3/H2 was conducted on excimer-laser-annealed (ELA) poly-Si. The amount of as-implanted damage was observed to increase with acceleration voltage. The measured values of as-implanted damage using a UV-transmittance was found to correlate well with the ones calculated using TRIM-code simulation. After activation annealing the sheet resistance generally decreases as the acceleration voltage increases. It, however, increases as the acceleration voltage increases under the conditions of severe doping and low temperature annealing. Results of UV-transmission Spectroscopy and Hall measurements revealed that uncured damage seems to be responsible for the rise in sheet resistance.

Abstract: Porous YSZ(8 mol% yttria-stabilized zirconia) was prepared by an acid leaching of ZnO-YSZ composite. The ZnO-YSZ composites were obtained by two different methods, a 1450 °C sintering of the mechanical mixture of ZnO and YSZ powders or a decomposition of Zn(NO3)2 deposited on YSZ and a subsequent sintering. The XRD (X-ray diffraction) pattern of the composite indicated that it was a mixture of ZnO and YSZ even after the sintering. Sharp edge or round edge of YSZ was observed in SEM (Scanning Electron Microscope) image of the porous-YSZ from the mixture of ZnO and YSZ, or Zn(NO3)2 deposited on YSZ, respectively. The porous YSZ from the composite having ZnO component greater than 60 wt% shows low mechanical strength. As the ZnO content of the composite increased, the porosity and gas permeability of the porous YSZ increased. From the result, it was suggested that ZnO is a candidate to generate pores in YSZ bulk or membrane.