Highly conductive and transparent aluminum- and gallium-doped zinc oxide (ZnO:Al and ZnO:Ga) thin films in place of indium tin oxide films have been prepared by using XeCl excimer laser ablation at relatively low temperatures. The impurity content of Al or Ga in the ZnO target was optimized on the basis of the measurements of resistivity, carrier concentration, and Hall mobility of the deposited transparent conducting ZnO films. The effects of substrate temperature on the properties of ZnO films were investigated. The crystalline, electrical and optical properties of the films were found to depend directly on substrate temperature during deposition. The minimum resistivity of 1.4×10−4 Ω cm was obtained for the ZnO:Al film prepared at a substrate temperature of 300 °C using a ZnO target with an Al2O3 content of 1% by weight (wt %). Moreover, the ZnO:Al film prepared at a substrate temperature of 100 °C showed a low resistivity value of 2.5×10−4 Ω cm. As for the ZnO:Ga film, on the other hand, the minimum resistivity value was 2.7×10−4 Ω cm for the film deposited at 300 °C using a ZnO target with a Ga2O3 content of 7 wt %. Furthermore, plasma etching of ZnO films employing a mixture of CH4 and H2 was carried out, and it was found that a small amount of CH4 gas enhanced the etching of ZnO films.

Ultraviolet absorption spectroscopy using a ring dye laser and a hollow cathode lamp was applied to measurement of Si(3p2, 1D2) and Si(3p2, 3P2) atom density decay in the afterglow of a radio frequency SiH4-Ar plasma. The dependence of the Si density decay rate on SiH4 and Ar partial pressure and also on the radio frequency input power was investigated, from which Si(3p2,1D2)-SiH4 reaction rate constant was determined to be (7.4+or-0.4)*10-10 cm3 molecule-1 s-1, the Si(3p2, 3P2)-SiH4 reaction rate constant (3.5+or-1.0)*10-10 cm3 molecule-1 s-1 and the diffusion coefficient for Si(3p2, 1D2) in Ar (at 320 K) (4.0+or-0.8)*104 cm2 Pa s-1.

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It is weIl known that the space charge accumulation gives a great influence on both the short-time and long-time breakdown strengths for the dc plastic insulation system: I n this paper , dc treeing phenomena initiated from a tip of the ne edle electrode inserted into the polyethylene specimen have been investigated under various condi tions. The characteristics of three kinds of tree observed , dc voltage tree, short-circuit tree and polarity reversal tree, according t o the expe rimental conditions were identified as a function of voltage rising speed, period of dc voltage p re-application, rest time to the short-circuit or the application of polarity reversed voltage, needle electrode materia l and temperature etc ..From these experimental results, the homo-space charge formation with a high electric stress was concluded, which induces an electric field distortion around the needle tip. In order to explain the length of tre e as a function of various factors mentioned above, a model for the space charge formation was proposed, inc luding the processes such as charge injection, trapping and its diffusion.

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