Polycrystalline Er-doped Y3Ga5O12 Nanofilms Fabricated by Atomic Layer Deposition on Silicon at a Low Temperature and the Exploration on Electroluminescence Performance

Polycrystalline erbium-doped Y3Ga5O12 garnet (YGG) nanofilms are deposited by atomic layer deposition on Si substrates after annealing down to 800 °C, based on which ∼1.53 μm electroluminescence (EL) devices are fabricated. The optimal EL performance depends on the adjustment of Y/Ga ratio and Ga2O3 interlayer thickness within the nanolaminates, which exert no prominent impact on the crystallization and film morphology of YGG nanofilms. EL spectra reveal that the crystalline structure after annealing impacts the surrounding environment of Er3+ ions, leading to different emission peaks. These silicon-based devices present a low turn-on voltage of ∼25 V, while the external quantum efficiency and maximum optical power density reach 2.51% and 10.03 mW cm-2, respectively. The EL is ascribed to the impact-excitation of doped Er3+ ions in polycrystalline YGG nanofilms by energetic electrons, the conduction mechanism of which is confirmed to be the Poole-Frenkel mode. These prototype devices possess excellent stability and can operate for up to 49 hours under continuous current injection, verifying the improvement of device performance by the utilization of gallium in the fabrication of garnet nanofilms. The Si-based YGG:Er EL devices are of promising potential for integrated optoelectronic applications.