Silicon-based PbS-CQDs infrared photodetector with high sensitivity and fast response

Silicon-based photodetectors as the main force in visible and near-infrared detection devices have been deeply embedded in modern technology and human society, but due to the characteristics of silicon itself, its response wavelength is generally less than 1100 nm. It is an interesting study to combine the state-of-art silicon processing with emerging infrared-sensitive Lead sulfide colloidal quantum dots (PbS-CQDs) to produce a photodetector that can detect infrared light. Here, we demonstrated a silicon-compatible photodetector that could be integrated on-chip, and also sensitive to infrared light which is owing to a PbS-CQDs absorption layer with tunable bandgap. The device exhibit extremely high gain which reaches maximum detectivity 3.95×1012 Jones, fast response 211/558 μs, and extremely high external quantum efficiency 4.96×105%, which is owing to new architecture and reasonable ligand exchange options. The performance of the device originates from the new architecture, that is, using the photovoltaic voltage generated by the surface of PbS-CQDs to change the width of the depletion layer to achieve detection. Besides, the performance improvement of devices comes from the addition of PbS-CQDs (Ethanedithiol treated) layer, which effectively reduces the fall time and makes the device expected to work at higher frequencies. Our work paves the way for the realization of cost-efficient high-performance silicon compatible infrared optoelectronic devices.