Study On Y₂O₃ Thin Film By RF Magnetron Reactive Sputtering

Diamond is an ideal material for airborne LWIR (8¹2μm) windows and domes with excellent properties in mechanics, electrics, calorifics and optics. However, diamond is easily subject to oxidation in air at temperatures higher than 750℃, and the optical transmittance is hence degraded greatly. In order to meet the requirements of the applications under high-speed or high-temperature, anti-oxidation and anti-reflective films must be prepared on the diamond surface. Yttrium oxide (Y2O3) is a promising anti-oxidation material for diamond with good physical, chemical and anti-oxidation properties. Great progresses have been made in the researches on Y₂O₃ anti-oxidation films overseas. But no domestic work has yet been done. Researches of this paper concentrate mostly on the preparations, components, structures and infrared transmission properties of Y₂O₃ films, which will establish a technical foundation for using diamond for high-speed IR windows and domes. The main research works and results are as follows:Anti-reflective films containing Y2O3 are designed on diamond substrates with OPFCAD software and the sensitive factor and deviation of the films' structure are analyzed. The designed results show that the average transmittances of both Y₂O₃//Diamond and Y₂O₃/AIN//Diamond systems over 8¹1.5μm waveband exceed 90%, and the maximal increased transmittance is up to 21%.Y₂O₃ films are prepared on silicon substrates through JGP560C magnetron sputtering apparatus in order to research the influences of the main depositing parameters, such as the RF power, gas pressure, Ar/O₂ gas flow ratio, and substrate temperature, on the film depositing rates, and thus the optimized parameters are obtained. The orthogonal experiment results show that the effects of RF power and gas pressure on the deposition rates is most significant, and the parameters to get high deposition rate are decided.XPS and XRD analyses as well as FTIR transmission spectrum tests are carried out. XPS analysis confirms the formation of the compound of Y2O3 XRD results show that the as-deposited Y2O3 films are mainly amorphous and after annealed at 800 °C become polycrystalline. FTIR results show that the average transmittance over 2000-3 000cm"1 of silicon substrate with Y2O3 films coated on both sides exceeds 90%, and the refractive indexes of the film are about 1.93.