Enhanced electroluminescence from silicon-based light-emitting devices with Mg0.4Zn0.6O/erbium-doped ZnO heterostructures by using ITO/MoO3 combined anode

We have realized the erbium (Er)-related visible and near-infrared (NIR) electroluminescence (EL) from the Mg_0.4Zn_0.6O/ZnO:Er/n⁺-Si heterostructured light-emitting device (LED) using the semi-transparent Au film as the anode, where the impact-excitation of Er³⁺ ions is enabled by hot holes that are generated in the Mg_0.4Zn_0.6O acceleration layer. However, it remains a challenge to simultaneously achieve more efficient injection of holes into Mg_0.4Zn_0.6O layer and stronger light emanation for the Mg_0.4Zn_0.6O/ZnO:Er/n⁺-Si heterostructured LED. Addressing this issue, we report on the substitution of an ITO/MoO₃ combined anode for the Au anode in the aforementioned LED to enhance the EL. Through the optimization of MoO₃ film thickness, the substitution of ITO/MoO₃ combined anode for Au anode leads to the enhanced EL from the Mg_0.4Zn_0.6O/ZnO:Er/n⁺-Si heterostructured LED with a factor of more than 5 in the visible region and with a factor of more than 13 in the NIR region. The higher transmittances and larger refraction indices in both visible and NIR regions and the better hole-injection capability of the ITO/MoO₃ combined anode, with respect to those of Au anode, are responsible for the significantly enhanced EL as mentioned above. This work sheds light on the application of ITO/MoO₃ combined anode into all-inorganic LEDs.