Kunio Akedo

LP‐5: Late‐News Poster: Plasma‐CVD SiNx / Plasma‐Polymerized CNx:H Multi‐layer Passivation Films for Organic Light Emitting Diodes

We have developed plasma-CVD SiNx / plasma-polymerized CNx:H multi-layer films to improve the longevity of passivated OLEDs for automobile applications. The films had high barrier against moisture even at high temperatures, because the thermal stress of the films was released by the soft CNx:H layers and no crack was produced.

Effect of Particle Size on the Magnetic Properties of Ni Nanoparticles Synthesized with Trioctylphosphine as the Capping Agent

Magnetic cores of passive components are required to have low hysteresis loss, which is dependent on the coercive force. Since it is well known that the coercive force becomes zero at the superparamagnetic regime below a certain critical size, we attempted to synthesize Ni nanoparticles in a size-controlled fashion and investigated the effect of particle size on the magnetic properties. Ni nanoparticles were synthesized by the reduction of Ni acetylacetonate in oleylamine at 220 °C with trioctylphosphine (TOP) as the capping agent. An increase in the TOP/Ni ratio resulted in the size decrease. We succeeded in synthesizing superparamagnetic Ni nanoparticles with almost zero coercive force at particle size below 20 nm by the TOP/Ni ratio of 0.8. However, the saturation magnetization values became smaller with decrease in the size. The saturation magnetizations of the Ni nanoparticles without capping layers were calculated based on the assumption that the interior atoms of the nanoparticles were magnetic, whereas the surface-oxidized atoms were non-magnetic. The measured and calculated saturation magnetization values decreased in approximately the same fashion as the TOP/Ni ratio increased, indicating that the decrease could be mainly attributed to increases in the amounts of capping layer and oxidized surface atoms.

Improvement of Durability in Silicon Nitride Barrier Films for Flexible OLED Displays under High Temperature and High Humidity Conditions

We have developed a new silicon nitride (SiNx) multilayer barrier film by a plasma-enhanced chemical vapor deposition (CVD) for a flexible organic light emitting diode (OLED), which consists of SiNx films in two different deposition conditions, that is, a transparent SiNx layer (tr-SiNx) deposited with NH 3 gas and an ultra-thin SiNx layer (cap-SiNx) deposited without NH 3 gas, which caps over the former layer. This barrier film is expected to exhibit high durability under high temperature and high humidity conditions even at high deposition rate over 100 nm / minute, because the transparent SiNx layer, that is easily oxidized under such conditions, is protected by the cap-SiNx layer and the interface between them, and also show good transparency, because the opaque cap-SiNx layer is enough thin to be almost transparent to visible light. Thus, the multi-layer SiNx barrier film indicates the specific features as a high barrier performance, high transparency, and high productivity, and makes it possible to apply flexible OLED displays to automobile use.

Highly insulated SrTiO/sub 3/ thin films

Electrical properties of RF magnetron sputtered SrTiO/sub 3/ (STO) thin films have been studied in view of application to diminish the influence of electro-magnetic noise to automobile IC. STO films with Ti rich composition (Ti/Sr=1.2) have high breakdown field of Ebd=2 MV/cm and high dielectric constant of /spl epsi//sub r/=140 up to frequency region of 2 GHz. In addition, characterization by TEM observation of STO films thus formed revealed that the films have complex columnar structure, which includes crystal grains and amorphous layers. Electrical properties of STO films obtained in this study can be explained in terms of the coexistence of crystal grains and amorphous layers.