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The impact of nano-bubbles on the laser performance of hafnia films deposited by oxygen assisted ion beam sputtering method
- Source :
- Applied Physics Letters. 115:251902
- Publication Year :
- 2019
- Publisher :
- AIP Publishing, 2019.
-
Abstract
- Hafnia is a high refractive index material used in the manufacturing of dielectric coatings for next generation lasers. The formation of defects during deposition is the major barrier to realizing high laser-damage resistant coatings for future high energy density laser applications. Understanding the precursors responsible for laser-induced damage in hafnia is therefore critical. In this work, we investigate the mechanism of laser-induced damage in 90-nm thick hafnia films produced by an oxygen assisted dual ion beam sputtering (IBS) process. Under pulsed, nanosecond ultraviolet laser exposure (355 nm, 8 ns), the laser-induced damage onset is found to be strongly dependent on the amount of argon and excessive oxygen entrapped in the nanobubbles within the hafnia films. The presence of nanobubbles is revealed and confirmed by small angle X-ray scattering and scanning/transmission electron microscopy coupled with high-angle annular dark-field. The damage onset is stable initially but decreases as the energy of oxygen goes beyond 100 eV. The damage initiation is ascribed to a laser-induced plasma generation within the nanobubbles through multiphoton ionization. The results reveal that nanobubbles formed in the IBS produced coatings are a potent precursor. Although nanobubbles are commonly present in IBS films, their negative impact on laser damage resistance of hafnia films has not been previously recognized. Our findings provide a fundamental basis for the development of potential mitigation strategies required for the realization of laser damage resistant hafnia films.
- Subjects :
- Materials science
Physics and Astronomy (miscellaneous)
chemistry.chemical_element
02 engineering and technology
Dielectric
medicine.disease_cause
01 natural sciences
law.invention
law
0103 physical sciences
Nano
medicine
010302 applied physics
Argon
biology
business.industry
Nanosecond
021001 nanoscience & nanotechnology
Laser
Hafnia
biology.organism_classification
chemistry
Transmission electron microscopy
Optoelectronics
0210 nano-technology
business
Ultraviolet
Subjects
Details
- ISSN :
- 10773118 and 00036951
- Volume :
- 115
- Database :
- OpenAIRE
- Journal :
- Applied Physics Letters
- Accession number :
- edsair.doi...........56247e4e36276fe9aba0cbc3ced7ea10