Colloidal Quantum-Dots/Graphene/Silicon Dual-Channel Detection of Visible Light and Short-Wave Infrared

Integration of infrared detectors with current silicon-based imagers would not only extend their spectral sensing range, but also enables numerous applications including thermal imaging, machine vision, and spectrometers. Here, we report the development of a dual-channel photodetector by depositing a colloidal quantum dot (CQDs) infrared photodiode onto a graphene/p-silicon Schottky junction to provide simultaneous visible and infrared photoresponse channels. The HgTe photodiode is patterned into a semitransparent mesh structure with varying fill factors so that the visible light reaches the silicon substrate. The graphene/silicon Schottky junction has a responsivity of ∼0.9 A/W in the visible and the infrared CQDs photodiode has a detectivity of ∼5 × 109 Jones at 2.4 μm for a filling factor of 0.1.