Abstract

Ta₂O₅ is a suitable high-index material for thermal resistive thin film applications, such as a component of reflector mirrors for projectors. Melting of Ta₂O₅ tablets by electron beam gun shows often the dissociation of starting Ta₂O₅ materials and gives rise of O₂ level during its melting. It is, therefore, necessary to continue a long time premelting process to get sufficient low oxygen level or stable vacuum pressure before starting appropriate deposition of Ta₂O₅ films. It requires not only disadvantageous long process time, but also it starts again endless oxygen outlet from the insufficiently melt parts of Ta₂O₅ when electric power applied to electron beam gun increases towards higher level for deposition. This results inevitably unstable deposition process and hence unstable refractive indices of Ta₂O₅ films obtained up to now.

© 1992 Optical Society of America