Electroluminescence from Er-doped ZnGa2O4 spinel nanofilms fabricated by atomic layer deposition on silicon

Abstract

Erbium doped ZnGa2O4 spinel nanofilms are fabricated by atomic layer deposition on Si substrates, the electroluminescence (EL) devices based on which present intense ∼1.53 μm near-infrared emission. The annealing above 1000 °C leads to significant evaporation loss of Zn in the deposited ZnO/Ga2O3 nanolaminates with the phase transition from zinc gallate to gallium oxide, together with the change on the splitting peaks in EL spectra, which results from the different impact on the adjacent crystal field of doped Er3+ ions. The relatively lower annealing temperature of 800 °C and a stoichiometry Ga/Zn ratio of 2.0 are preferable for the optimization of EL performance, resulting in an external quantum efficiency of 0.31% with the decay lifetime of 815 μs. The EL is confirmed to originate from the impact-excitation by hot-electron injected via Poole-Frenkel mechanism into the ZnGa2O4 matrix. The prototype devices could operate continuously exceeding 5 h while maintaining ∼90% of the initial EL intensity. This work is believed to pave the way for the fabrication of multi-oxides with designed composition and structure, and the development of Si-based EL devices for integrated optoelectronic applications.