High quality silicon: Colloidal quantum dot heterojunction based infrared photodetector

The integration of silicon (Si) and nanomaterials with infrared light harvesting capability is a promising approach to fabricate large area infrared light detecting arrays. However, the construction of a high quality junction between Si and small bandgap colloidal quantum dots (CQDs) remains a challenge, which limited their photodetecting performance in the short wavelength infrared region (1.4 μm–3 μm). Herein, a layer of solution processed ZnO nanoparticles was inserted between silicon and CQDs to passivate the surface dangling bond of silicon. This significantly reduces the carrier recombination between Si and CQDs. Meanwhile, the formation of the Si:CQD heterojunction structure enables effective carrier extraction. As a result, the photodetector shows the detecting range to the short wavelength infrared region (0.8 eV) and achieves a standard detectivity of 4.08 × 1011 Jones at a bias of −0.25 V at room temperature.