Electroluminescent polycrystalline Er-doped Lu3Al5O12 nanofilms fabricated by atomic layer deposition on silicon

Abstract

The sub-nanometer composition and interlayer thicknesses of the silicon-based Lu2O3/Al2O3 nanolaminates are regulated by atomic layer deposition, to fabricate polycrystalline Er-doped Lu3Al5O12 (LuAG:Er) nanofilms and optimize their electroluminescence (EL) performance. The Lu:Al ratio in the nanolaminates strongly influences the crystallization temperature and the morphologies of garnet nanofilms, while the ratio sufficiently higher than stoichiometry promotes the crystallization into micrometer grains after annealing above 900 °C. EL devices based on these polycrystalline LuAG:Er nanofilms present the characteristic 1.53 µm EL from Er3+ ions, exhibit the optimal external quantum efficiency of 10.0% and the power efficiency of 0.123%, with fluorescence lifetime measured as 1.2–1.8 ms. The EL efficiencies and lifetime are closely correlated to the Lu:Al ratio and doping concentrations. The electron injection within the LuAG:Er devices is dominated by the Fowler-Nordheim tunneling, resulting in the impact-excitation of doped Er3+ ions and the characteristic emissions. This work explores the deposition of complex oxide nanofilms with designed composition and crystallinity at low temperature, and the development of Si-based optoelectronic devices from garnet films.