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High-rate reactive magnetron sputtering of zirconia films for laser optics applications
- Source :
- Applied Physics A. 116:1229-1240
- Publication Year :
- 2014
- Publisher :
- Springer Science and Business Media LLC, 2014.
-
Abstract
- ZrO2 exhibits low optical absorption in the near-UV range and is one of the highest laser-induced damage threshold (LIDT) materials; it is, therefore, very attractive for laser optics applications. This paper reports explorations of reactive sputtering technology for deposition of ZrO2 films with low extinction coefficient k values in the UV spectrum region at low substrate temperature. A high deposition rate (64 % of the pure metal rate) process is obtained by employing active feedback reactive gas control which creates a stable and repeatable deposition processes in the transition region. Substrate heating at 200 °C was found to have no significant effect on the optical ZrO2 film properties. The addition of nitrogen to a closed-loop controlled process was found to have mostly negative effects in terms of deposition rate and optical properties. Open-loop O2 gas-regulated ZrO2 film deposition is slow and requires elevated (200 °C) substrate temperature or post-deposition annealing to reduce absorption losses. Refractive indices of the films were distributed in the range n = 2.05–2.20 at 1,000 nm and extinction coefficients were in the range k = 0.6 × 10−4 and 4.8 × 10−3 at 350 nm. X-ray diffraction analysis showed crystalline ZrO2 films consisted of monoclinic + tetragonal phases when produced in Ar/O2 atmosphere and monoclinic + rhombohedral or a single rhombohedral phase when produced in Ar/O2 + N2. Optical and physical properties of the ZrO2 layers produced in this study are suitable for high-power laser applications in the near-UV range.
Details
- ISSN :
- 14320630 and 09478396
- Volume :
- 116
- Database :
- OpenAIRE
- Journal :
- Applied Physics A
- Accession number :
- edsair.doi...........fc8331139bf7632b29a6794ad9e0d7d1