Blue Electroluminescent Al₂O₃/Tm₂O₃ Nanolaminate Films Fabricated by Atomic Layer Deposition on Silicon

Realization of a silicon-based light source is of significant importance for the future development of optoelectronics and telecommunications. Here, nanolaminate Al₂O₃/Tm₂O₃ films are fabricated on silicon utilizing atomic layer deposition, and intense blue electroluminescence (EL) from Tm³⁺ ions is achieved in the metal-oxide-semiconductor structured luminescent devices based on them. Precise control of the nanolaminates enables the study on the influence of the Tm dopant layers and the distance between every Tm₂O₃ layer on the EL performance. The 456 nm blue EL from Tm³⁺ ions shows a maximum power density of 0.15 mW/cm². The EL intensities and decay lifetime decrease with excessive Tm dopant cycles due to the reduction of optically active Tm³⁺ ions. Cross-relaxation among adjacent Tm₂O₃ dopant layers reduces the blue EL intensity and the decay lifetime, which strongly depends on the Al₂O₃ sublayer thickness, with a critical value of ~3 nm. The EL is attributed to the impact excitation of the Tm³⁺ ions by hot electrons in Al₂O₃ matrix via Poole⁻Frenkel mechanism.