A Plasmon-Enhanced SnSe₂ Photodetector by Non-Contact Ag Nanoparticles

The 2D layered materials are promising candidates for broadband, low-cost photodetectors. One deficiency of 2D materials is the relatively low absorbance of light, limiting the applications of the 2D photodetectors. Doping of plasmonic nanoparticles into 2D materials may enhance the optical absorbance owing to the localized surface plasmonic resonance (LSPR) effect; however, considerable defects may be introduced into the 2D materials at the same time, resulting in certain degradation of device performance. Here, a novel design of 2D photodetectors with enhanced photoresponsivity by non-contact plasmonic nanoparticles (NPs) is proposed, consisting of a hybrid structure of few-layer SnSe₂ transferred a fused silica (SiO₂ ) plate with embedded Ag NPs. The system of Ag NPs-in-SiO₂ shows strong LSPR effect with significantly enhanced optical absorption, acting on SnSe₂ in a non-contact configuration. Benefiting from well-preserved intrinsic features of SnSe₂ and LSPR effect, the responsivity of the photodetector is enhanced by 881 times with the bias voltage of 0.1 V, which is superior to previously reported results of plasmon-enhanced 2D photodetectors. Moreover, the SiO₂ with embedded Ag NPs is recyclable and can be easy to be recombined with different 2D materials. This work offers additional strategy for development of efficient, low-cost 2D photodetectors by using plasmonic NPs.