Publication: Eu activation in beta-Ga_2O_3 MOVPE thin films by ion implantation
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In this work, we have established the effects of Eu implantation and annealing on beta-Ga_2O_3 thin films grown by metal organic vapor phase epitaxy (MOVPE) on sapphire substrate. The study is based on the combined information from structural and optical techniques: X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), cathodoluminescence (CL), photoluminescence (PL), and photoluminescence excitation (PLE). The thin films were implanted with a fluence of 1 x 10^15 Eu.cm^-2 and annealed at 900 degrees C. Neither significant changes in peak width or position nor additional peaks related to Eu complexes were detected in the XRD 2 theta-omega scans. RBS results and SRIM simulation are in good agreement, revealing that no Eu diffusion to the surface occurs during annealing. For the used implantation/annealing conditions, the Eu ion penetration depth reached similar to 130 nm, with a maximum concentration at similar to 50 nm. Furthermore, CL and PL/PLE results evidenced the optical activation of the Eu^3+ in the beta-Ga_2O_3 host. The detailed study of the Eu^3+ intra-4f shell transitions revealed that at least one active site is created by the Eu implantation/annealing in beta-Ga_2O_3 thin films grown on sapphire. Independently of the beta-Ga_2O_3 film thickness, well controlled optical activation of implanted Eu was achieved.
©The Author(s) 2019. Published by ECS. The authors acknowledge financial support from FEDER funds through the COMPETE 2020 Programme and National funds through FCT - Portuguese Foundation for Science and Technology (FCT) under the projects UID/CTM/50025/2013, POCI-01-0145-FEDER-028011 & LISBOA-01-0145-FEDER-029666, and UID/FIS/50010/2019. B Mendez and E Nogales are grateful for the financial support from the MINECO (Projects No. MAT-2015-65274-R-FEDER and PCIN-2017-106). We especially thank Dr. Daniela Gogova for providing the as-grown samples of this study, for the availability and the fruitful discussions about β-Ga_2O_3 MOVPE growth.