CVD SYNTHESIS OF THIN FILMS OF RARE EARTH AND HEAVY METAL FLUORIDES,AND OPTICAL AND/OR ELECTRICAL FUNCTIONS

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The object of the present research is (i) development of a microwave ECR plasma CVD equipment, (ii) synthesis of volatile comlpexes of rare earth and other metal elements, (iii) preparation of rare earth-containing fluoride glasses by microwave ECR plasma CVD process, and (iv) evaluation of optical and electrical properties of the prepared rare earth-containing fluoride glasses.(i) A microwave ECR plasma CVD equipment was designed and constructed in cooperation with HIRANO KOON Inc. Some of the main performance are microwave oscillation number of 2.45GHz, oscillation power of max. 1000W,deposition area of 20x20mm, deposition temperature of max. 200ﾟC,gas supply systems of Ar, O_2 and SF_6, and four complex-monomer introduction lines.(ii) The followings are required for volatile complexes of rare earth and other metal elements which are available for microwave ECR plasma CVD process ; Those vaporize at lower temperatures without decomposition and, in addition, as a monomer at almost the same temperature. As volatile complexes of rare earth and other metal elements, various beta-diketone complexes were chosen.(iii) At first, synthesis of a ZrF_4-BaF_2 film was attempted by using Zr (HFA) _4 and Ba (DFHD) _2 as beta-diketones of Zr and Ba, respectively, and by employing CaF_2 as a substrate. Microwave ECR plasma CVD with SF_6 as a fluorinating gas and Ar as a carrier gas gave amorphous ZrF_4-BaF_2 film of a few mum thickness. Its X-ray powder pattern indicates that the composition is close to 67ZrF_4・33BaF_2. Synthesis of rare earth-containing fluoride glasses is now in progress by using DPM complexes.