Integrated ECR-PECVD and magnetron sputtering system for rare-earth-doped Si-based materials

• Published in: Surface & coatings technology 2018-02, Vol.336, p.99-105
• Main Authors: Miller, J.W., Khatami, Z., Wojcik, J., Bradley, J.D.B., Mascher, P.
• Format: Article
• Language: English
• Subjects: Backscattering; Chemical vapor deposition; Doping; Film thickness; Integrated ECR-PECVD and magnetron sputtering; Magnetron sputtering; Materials science; Morphology; Optical activity; Optical properties; Organic chemistry; Partial pressure; Plasma enhanced chemical vapor deposition; Plasma physics; Rare earth elements; Rare-earth-doped; Recoil; Refractivity; Silicon; Silicon dioxide; Silicon oxides; Spectroellipsometry; Sputtering power; Terbium; Thin films; Transmission electron microscopy
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2017.08.051

We report on a novel hybrid deposition technique to dope silicon-based materials with optically active elements in a plasma enhanced chemical vapor deposition (PECVD) process using a magnetron sputtering source. This approach is in contrast to traditional methods of rare-earth doping of PECVD films that utilise a metal organic precursor to introduce the rare earth species into the host matrix. We investigated the influence of the sputtering power applied to the rare earth metal target, in this case terbium, and the argon (Ar) partial pressure on the optical properties and composition of terbium-doped silicon oxide (SiOx:Tb3+) thin films. The film morphology was determined using high-resolution transmission electron microscopy, Rutherford backscattering spectrometry, and elastic recoil detection. We demonstrated that employing this novel technique provides a wider range of control of the doping level, yet delivers a similar rare earth (terbium) content to that which can be achieved using a traditional metal organic process. While the terbium concentration was strongly influenced by the sputtering power, it was only slightly affected by the Ar partial pressure. The refractive index was calculated from variable angle spectroscopic ellipsometry analysis and shows a direct relationship with the sputtering power whereas the film thickness shows an inverse relationship. The optically active Tb3+ ions were successfully excited within the silicon dioxide host matrix and the green Tb3+ emission was visible by the naked eye. •A novel technique combining PECVD with magnetron sputtering for RE-doped Si-based films was calibrated.•Tb3+ emission was successfully excited in a silicon dioxide host.•The Tb content and refractive index increased with the increase of the sputtering power.•Ar partial pressure was found to not affect the Tb concentration and refractive index.•This custom integrated system provided a high control over the dopant levels.