Abstract
In this paper, we prepared a novel structure to enhance the electroluminescence intensity from Si quantum dots/SiO2multilayers. An amorphous Si/SiO2 multilayer film was fabricated by plasma-enhanced chemical vapor deposition on a Pt nanoparticle (NP)-coated Si nanopillar array substrate. By thermal annealing, an embedded Si quantum dot (QDs)/SiO2 multilayer film was obtained. The result shows that electroluminescence intensity was significantly enhanced. And, the turn-on voltage of the luminescent device was reduced to 3 V. The enhancement of the light emission is due to the resonance coupling between the localized-surface-plasmon (LSP) of Pt NPs and the band-gap emission of Si QDs/SiO2 multilayers. The other factors were the improved absorption of excitation light and the increase of light extraction ratio by surface roughening structures. These excellent characteristics are promising for silicon-based light-emitting applications.
Highlights
In this paper, we prepared a novel structure to enhance the electroluminescence intensity from Si quantum dots/SiO2multilayers
It was reported that the light emission of Si-QDs is based on the radiative recombination occurring at surface defect states surrounding the Si-QD core
The Pt NPs were used for their localized surface plasmons and the nanopillar array was used for surface roughening
Summary
To get more information on the surface morphology, the samples were characterized by atomic force microscopy (AFM). Is reduced obviously.The enhancement of the light emission is due to the resonance coupling between the LSP of Pt NPs. When the light emission wavelength of Si QDs/SiO2 multilayer is close to the extinction peak of Pt nanoparticles, this coupling process occurs. Considering the index of Si and SiO2, which is about 3.4 and 1.5, it can be estimated that the light escaping from the flat sample without Pt NPs-coated Si nanopillar is 8.3%. It is interesting to find that the light reflection from the front surface is obviously suppressed for the nano-patterned samples, indicating the anti-reflection characteristics for nano-patterned Si substrates It has been reported enhanced optical absorption was achieved from the Si-based nano-cone or nano-pillar structures and the antireflection[32]. Both of them make the carrier injection into the Si QDs/SiO2 system easier, the EL intensity can be increased
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