Layer growth of high-quality BaSO4:Mn6+ using liquid phase epitaxy

D. Ehrentraut, Markus Pollnau

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    Abstract

    Single-crystalline host materials doped with transition-metal ions are of high interest for applications as tunable lasers. Mn6+ ions exhibit broadband luminescence, however, Mn6+-doped crystals or waveguide structures could as yet not be grown in sufficient quality. The active material has to be free of inclusions or defects larger than λ/10, with λ, the wavelength of the porpagating beam. The interface between active layer and substrate must be optically flat to receive low-loss guiding properties. Finally, in the case of homo-epitaxy of BaSO4, the doped layer has to be arranged on the substrate (001) direction, because … . The growth temperature of BaSO4:Mn6+ is limited by the decomposition of BaSO4 at 1590°C, its phase transition above 1010°C, and especially the chemical reduction of the manganese dopant from Mn6+ to Mn5+ above 620°C. Therefore, the growth of BaSO4:Mn6+ from a solution at lower temperatures is the most suitable method. Liquid phase growth is close to the thermodynamic equilibrium and has enabled us to grow high-quality layers. First, we prepared undoped BaSO4 crystals of 10 x 5 x 1 mm3 in a, b, and c-direction, respectively, using the flux method with LiCl as solvent. Subsequently, growth of high-quality undoped BaSO4 was performed by liquid phase epitaxy (LPE), using the additive ternary CsCl-KCl-NaCl solution. We obtained crystalline layers free of inclusions, grown in the Frank-Van der Merwe mode (layer-by-layer growth). Finally, layers of BaSO4:Mn6+ were fabricated with thicknesses up to 150 μm, at growth rates of 3 μm/h and temperatures of 500–580°C. The thickness was controllable with a precision of 0.1 μm. The Mn6+ concentration in the doped layer was up to 1 mol.% with respect to S6+. In collaboration with the University of Hamburg, absorption and emission spectra were measured, which confirmed that the manganese ion was incorporated in the layer solely in its sextavalent oxidation state. Room-temperature luminescence in the wavelength range 850-1600 nm was observed.
    Original languageUndefined
    Pages198-199
    Number of pages1
    Publication statusPublished - Apr 2002
    EventMRS Spring Meeting 2002 - San Francisco, United States
    Duration: 1 Apr 20025 Apr 2002

    Conference

    ConferenceMRS Spring Meeting 2002
    CountryUnited States
    CitySan Francisco
    Period1/04/025/04/02

    Keywords

    • EWI-18056
    • IR-72125
    • IOMS-APD: Active Photonic Devices

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