Multiresonant Grating to Replace Transparent Conductive Oxide Electrode for Bias Selected Filtering of Infrared Photoresponse.

Optoelectronic devices rely on conductive layers as electrodes, but they usually introduce optical losses that are detrimental to the device performances. While the use of transparent conductive oxides is established in the visible region, these materials show high losses at longer wavelengths. Here, we demonstrate a photodiode based on a metallic grating acting as an electrode. The grating generates a multiresonant photonic structure over the diode stack and allows strong broadband absorption. The obtained device achieves the highest performances reported so far for a midwave infrared nanocrystal-based detector, with external quantum efficiency above 90%, detectivity of 7 × 1011 Jones at 80 K at 5 µm, and a sub-100 ns time response. Furthermore, we demonstrate that combining different gratings with a single diode stack can generate a bias reconfigurable response and develop new functionalities such as band rejection.