Sandwich-structured Cu2O photodetectors enhanced by localized surface plasmon resonances

We report here a facile wet-chemical route to fabricate high performance Cu2O-based plasmonic photodetectors. The Cu2O active layer is sandwiched between Au nanoparticles (Au NPs) and a corrugated Au thin film electrode. We find that the presence of Au NPs will affect the nucleation process of Cu2O thin film on ITO, resulting in different surface morphology, and the localized surface plasmons (LSPs) of Au NPs can greatly increase resonant absorption of the incident light. We show, using I-V and photoresponse measurements, that the sample decorated with Au NPs exhibit greatly improved photo-to-dark current ratio and photoelectric conversion efficiency, with enhancement ratios of 199.7% and 54.3% compared with the sample without Au NPs, respectively. We attribute the observations mainly to optical effects of LSPs, and the effects of the corrugated Au electrode on light reflection are also discussed.