Tunable quantum dot arrays as efficient sensitizers for enhanced near-infrared electroluminescence of erbium ions.

Under electrical pumping conditions, high-efficiency Si-based near-infrared light generation and amplification on a chip have long been pursued for future optical interconnection technology. However, the overall performance of Si-based near-infrared electroluminescence (EL) devices, including the overall efficiency, turn-on voltage and stability under operational conditions, can rarely meet the requirements of monolithic optoelectronic integration. In this work, we designed a confined crystallization growth strategy for fabricating metal oxide quantum dot (QD) arrays embedded in Si-based films as sensitizers of Er ions. Through the precise control of particle size and number density of QD sensitizers, the near-infrared photoluminescence (PL) emission of Er ions can be enhanced by more than three orders of magnitude. More significantly, such hierarchical control over the regular arrangement of QD arrays not only considerably enhances the resonance energy transfer efficiency, but also offers an effective conduction path for carrier transport. Therefore, the corresponding near-infrared EL device exhibits a decreased turn-on voltage of 4.5 V, a high external quantum efficiency of 0.7%, and a long operational lifetime of more than 1000 hours, making this device superior to most Si-based on-chip near-infrared EL devices. This well-controlled metal oxide QD array represents an ideal sensitizer to effectively promote the EL emission of rare earth ions and reduce the turn-on voltage. Meanwhile, the analysis of the carrier transport mechanism paves the way for future research into resonance energy transfer under electrical pumping conditions.