Upconversion nanoparticles extending the spectral sensitivity of silicon photodetectors to λ = 1.5 μm

The telecommunication wavelength of λ = 1.5 μm has been playing an important role in various fields. In particular, performing photodetection at this wavelength is challenging, demanding more performance stability and lower manufacturing cost. In this work, upconversion nanoparticle (UCNP)/Si hybrid photodetectors (hybrid PDs) are presented, made by integrating solution-processed Er³⁺-doped NaYF₄ upconversion nanoparticles (UCNPs) onto a silicon photodetector. After optimization, we demonstrated that a layer of UCNPs can well lead to an effective spectral sensitivity extension without sacrificing the photodetection performance of the Si photodetector in the visible and near-infrared (near-IR) spectrum. Under λ = 1.5 μm illumination, the hybrid UCNPs/Si-PD exhibits a room-temperature detectivity of 6.15 × 10¹² Jones and a response speed of 0.4 ms. These UCNPs/Si-PDs represent a promising hybrid strategy in the quest for low-cost and broadband photodetection that is sensitive in the spectrum from visible light down to the short-wave infrared.