Optimization of the electroluminescence from SiNx-based light-emitting devices by modulating the size and morphology of silver nanostructures.

A maximal enhancement of ~6.5 times of the external quantum efficiency (EQE) for SiNx-based light-emitting devices (LEDs) is achieved by magnetron sputtering a silver nanostructures layer onto the active matrix. The enhancement of EQE is affected by the dimension and morphology of silver nanostructures, which can be controlled by the sputtering time and the post treatment of rapid thermal annealing. The optimal size of silver nanostructures is about 100 nm in diameter by comparing the integrated electroluminescence intensity under the same input power. The optimization of EQE for SiNx-based LEDs is discussed by considering the contributions of the enhancement of light-extraction efficiency induced by the surface roughening of the front electrode, internal quantum efficiency due to the coupling between excitons and localized surface plasmons, and carrier injection efficiency. Our work may provide an alternative approach for the fabrication of Si-based light sources with promising luminescence efficiency.