Interface Modification by Ga2O3 Atomic Layers within Er-Doped GeO2 Nanofilms for Enhanced Electroluminescence and Operation Stability

Abstract

For silicon-based devices using dielectric oxides doped with rare earth ions, their electroluminescence (EL) performance relies on the sufficient carrier injection. In this work, the atomic Ga₂O₃ layers are inserted within the Er-doped GeO₂ nanofilms fabricated by atomic layer deposition (ALD). Both Ga(CH₃)₃ and Ga(C₂H₅)₃ could realize the ALD growth of Ga₂O₃ onto the as-deposited GeO₂ nanofilm with unaffected deposition rates. The interfacial defects introduced by atomic Ga₂O₃ layers decrease the threshold voltage while increasing the tolerable injection current of the EL devices; the 1530 nm emissions from the 600 °C-annealed Ga₂O₃/GeO₂:Er nanolaminate devices achieve the optical power density of 16.2 mW/cm², with the excitation efficiency increased to 12.5%. Moreover, the interface modification by atomic Ga₂O₃ layers significantly prolongs the operation time of these prototype devices, reaching 5.21 × 10⁴ s for the optimal one. High-temperature annealing above 800 °C results in the decomposition of GeO₂ and leaves reticular porous nanofilms. The conduction mode within these amorphous Ga₂O₃/GeO₂:Er nanolaminates conforms to the trap-assisted tunneling mechanism, with the depths of defect states lowered by the interfacial Ga₂O₃ layers. These Ga₂O₃/GeO₂:Er nanolaminates with improved EL performance demonstrate new potential in the utilization of ALD GeO₂ nanofilms in silicon-compatible optoelectronics.