Planar, narrowband, and tunable photodetection in the near-infrared with Au/TiO2 nanodiodes based on Tamm plasmons
There is an increasing interest in the hot-electron photodetection due to the extended photoresponse well below the semiconductor band edge. However, the photoresponsivity is extremely low and the employed metallic nanostructures used to excite surface plasmons (SPs) for the improved quantum yield are too complex for practical applications. Here, we show that by exciting Tamm plasmons (TPs), the planar device consisting of a thin metal film of 30 nm on a distributed Bragger reflector (DBR) can absorb ~ 93% of the incident light, resulting in a high hot-electron generation that is over 34-fold enhanced compared to that of the reference without the DBR. Besides, the electric field increases with the light penetration depth in the metal, leading to the strongly concentrated hot-electron generation near Schottky interface. As a result, the photoresponsivity can be over 30 (6) times larger than that of the reference (conventional grating system). Moreover, the planar device exhibits an easily tuned working wavelength from the visible to the near-infrared, a sustained performance under oblique incidences, and a multiband photodetection functionality. The proposed strategy avoids the complicated fabrication of the metallic nanostructures, facilitating the compact, large-area, and low-cost photodetection, biosensing, and photocatalysis applications.