Nanocrystal-Based Active Photonics Device through Spatial Design of Light-Matter Coupling

The integration of photonic structures in nanocrystal (NC)-based photodetectors has been demonstrated to improve device performances. Furthermore, bias-dependent photoresponse can be observed in such devices as a result of the interplay between hopping transport and inhomogeneous electromagnetic field. Here, we investigate the main physical concepts leading to a voltage-dependent photoresponse. We first bring evidence of bias-dependent carrier mobilities in a NC array over a wide range of temperatures. Then, we fabricate an infrared sensing device using HgTe NCs, where the electrodes also play the role of a grating, inducing a spatially inhomogeneous absorption. The obtained device exhibits a significant bias-dependent photoresponse while possessing a competitive detection performance in the extended short-wave and mid-wave infrared, with detectivity reaching 7 × 1010 Jones at 80 K and a fast response time of around 70 ns. This work provides the foundation for further advancements in NC-based-active photonics devices.