Organic Photodiode Integration on Si Substrates beyond 1000 nm Wavelength

Organic photodiode integration on the Si readout circuit offers a solution for extending the sensitivity beyond 1000 nm. In this work, we report the way to integrate organic photodiodes on Si substrates with metals that are complementary metal–oxide–semiconductor process-compatible as bottom electrodes, such as titanium nitride (TiN), tungsten (W), and aluminum (Al). We report on a high-efficiency near-infrared sensor enabled by employing TiN and W as bottom electrodes, with an external quantum efficiency of ∼50% at 940 nm and ∼70% at 1030 nm, a dark leakage current density of 15 nA/cm2, a bandwidth of 15 kHz at −4 V, and a dynamic range of ∼100 dB. Low resistivity and inert properties of TiN make it form a good interface with the organic active layer, leading to an ideal bottom-contact metal for the organic photodiode when integrated on the Si substrate.