Bright white electroluminescence from polycrystalline dysprosium-doped yttrium gallium garnet nanofilms fabricated by atomic layer deposition on silicon

Abstract

Bright white emission is obtained under electrical excitation from dysprosium doped Y₃Ga₅O₁₂ garnet (YGG:Dy) nanofilms fabricated by atomic layer deposition on silicon substrates. Electroluminescence (EL) composed of yellow (580 nm) and blue (482 and 492 nm) emission corresponds to the CIE chromaticity coordinates of (0.3568, 0.3807) and a CCT of ∼4700 K and can be used for lighting and displays. The crystallization and micro-morphology of polycrystalline YGG:Dy nanolaminates are explored by adjusting the annealing temperature, Y/Ga ratio, Ga₂O₃ interlayer thickness and Dy₂O₃ dopant cycle. The near-stoichiometric device annealed at 1000 °C presents optimal EL performance with the maximum external quantum efficiency and the optical power density reaching 6.35% and 18.13 mW cm⁻², respectively. The EL decay time is estimated to be 273.05 μs, with a large excitation section of 8.33 × 10⁻¹⁵ cm². The conduction mechanism is confirmed to be the Poole–Frenkel mode under operation electric fields and the impact-excitation of Dy³⁺ ions by energetic electrons results in emission. Bright white emission from Si-based YGG:Dy devices can provide a new route to developing integrated light sources and display applications.