Eu activation in beta-Ga_2O_3 MOVPE thin films by ion implantation

Abstract

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.