Infrared hot-carrier photodetection based on planar perfect absorber.

Hot-carrier based photodetectors are independent on the semiconductor bandgap, thus paving a new paradigm of photovoltaic conversion. Herein, we propose a non-nanostructured and multilayered metal/insulator/transparent conductive oxide/silica/reflector system, and explore in detail the optical response and the electrical transport in the device via the finite-element electromagnetic simulation and the probability-based analytical carrier-transport calculation. Results show that the planar system can function as a planar perfect absorber at the targeted wavelength under the inbuilt cavity resonance with a very high tunability by tailoring the cavity length and the metal thickness. Moreover, a strong asymmetrical absorption is formed in the two electrode layers, yielding strong unidirectional photocurrents and output power densities. This Letter suggests a more simple and feasible way to realize hot-carrier infrared photodetectors.