Atomic Layer Deposition and Electroluminescence of Er-Doped Polycrystalline Lu3Ga5O12 Nanofilms for Silicon-Based Optoelectronics

Er-doped Lu3Ga5O12 garnet (LuGG:Er) nanofilms are obtained by the crystallization of Lu2O3/Er2O3/Ga2O3 nanolaminates fabricated using atomic layer deposition on silicon. The temperature required for garnet crystallization is independent of the Lu/Ga ratios and the interlayer thickness in the nanolaminates, and a threshold temperature of 800 °C is identified, ascribing to the easier migration and reconstruction of the gallium component. The efficiencies and lifetime of the characteristic 1.53 μm electroluminescence (EL) from Er3+ ions within polycrystalline LuGG:Er nanofilms are correlated with the Lu/Ga ratios, and a higher doping concentration of 3.5 mol % is preferable. The optimal device exhibits an external quantum efficiency of 2.5% and a power efficiency of 5.2 × 10–4, with the maximum optical power density reaching 4.9 mW/cm2 and the fluorescence lifetime longer than 2 ms. The electron injection within the LuGG:Er devices follows the trap-assisted tunneling mechanism under the operating electric field, resulting in the impact excitation of Er3+ ions. The prototype LuGG:Er device operates stably for ∼9.2 h while maintaining 90% of the initial EL intensity. This work further explores the deposition of compound oxide nanofilms with controlled composition and crystallinity at low temperature and Si-based garnet nanofilms for the optoelectronic applications.