Er-Doped MgAl₂O₄ Nanofilms Enabling Highly Efficient Near-Infrared Electroluminescence from the Silicon-Based MOS Devices Fabricated by Atomic Layer Deposition

Er3+-doped polycrystalline MgAl2O4 (MAO:Er) spinel nanofilms are deposited via atomic layer deposition, and the metal-oxide-semiconductor light emitting devices are fabricated. The crystallinity and morphology of the MAO:Er nanofilms are explored by modifying the annealing temperatures, Al2O3/MgO ratios and Er2O3 dopant cycles. The similar electroluminescence (EL) emissions peaking at 1530 nm indicates the identical crystal field environment for the doped Er3+ ions. The concentration quenching is verified to occurs via the energy transfer among the neighboring Er3+ ions. The optimal device (800 degrees C-annealed, Al2O3/MgO ratio close to stoichiometry, Er3+: 1.85 mol%) yields the highest external quantum efficiency of 28%, the power efficiency of 0.32% and the optical power density of 14.62 mW cm(-2). The smooth MAO:Er spinel nanofilms with the low refractive index and high resistance ensure the highly efficient light extraction and the generation of energetic electrons for the impact excitation of Er3+ ions. The trap-assisted tunneling under operation electric field dominates the conduction mechanism for the EL emissions. The estimated decay lifetime of 1154.4 mu s and a large-stimulated emission cross-section in the order of 10(-15)-10(-14) cm(2) are revealed from the EL emissions. Intense near-infrared emissions from these Si-based MAO:Er devices have great potential in the optoelectronic applications.