Mechanisim of Properties generation and Formation of Ceramic Thin Film with Varistor and PTCR Properties

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The varistor and PTC ceramics is very importan electronic parts for electronic products. These ceramics have been used as the sintered materials. The origin for property generation is due to the interface of each grain boundary in the sintered body. However, the sintered elecrtronic parts have some limitation for decreasing these size.The purpose of this study is to realize the thin film varistor and PTC parts using the some thin film formation method, mainly MOVCD and CSD (chemical solution deposition). The main materials for study are SrTiO_3, BaTiO_3 and these solid solution, and PbTiO_3, PZT having perovskite structure.Through above studies, the following useful results were obtained. And we succeeded in preparation of varistor and PTC thin film.(1) preparation of semiconductive, epitaxial thin film of Nb and La doped BaTiO_3 and SrTiO_3(2) mechanism of doping process and the situation of dopant atom in the perovskite structure thin film(3) preparation of Bi doped semiconductive SrTiO_3 thin film by MOCVD(4) The origin of varistor property in Bi doped SrTiO_3 film in due to the interface of domains with different orientation(5) Preparation of Bi doped semiconductive BaTiO_3 using chemical solution process suchi as MOD and CSD(6) Varistor phenomena was appeared on I-V characteristics for thin film CSD process and the mechanism was discussed(7) PTC phenomena was appeared around 125℃ for Bi doped BaTiO_3 thin film using CSD process