Enhancing Broad Band Photoresponse of 2D Transition-Metal Dichalcogenide Materials Integrated with Hyperbolic Metamaterial Nanocavities

Transition-metal dichalcogenides (TMDCs) are becoming an important material platform for constructing atomically thin optoelectronic devices, mostly due to their direct-to-indirect band gap tunability depending on their thickness and their ease of integration with various material platforms. One of the most challenging applications of TMDCs is their utilization as efficient photodetectors, mostly due to their nanoscale thickness, which limits their light absorption. To enhance the photodetection capabilities of TMDCs, one needs to adopt schemes for light-matter interaction enhancement. In this regard, the platform of hyperbolic metamaterial (HMM) nanocavities with indefinite dispersion and localized electromagnetic fields holds a great promise to enhance light-matter interactions. Motivated by the need for improving the performance of atomically thin photodetectors and considering the capabilities of HMMs, we hereby demonstrate a broadband photodetector with enhanced absorption based on the integration of TMDs with HMMs. Specifically, we have designed, fabricated, and experimentally characterized on-resonance and off-resonance photodetectors using a few layers of MoTe₂ and MoS₂, respectively. Overall, we observed an 8-fold (on-resonance) and 2.5-fold (off-resonance) enhancement of the photocurrent due to a localized electric field around each nanocavity. This enhancement of the localized electric field is also verified by full wave finite difference time domain simulations. The demonstrated photodetector approach provides an efficient strategy for designing ultrathin HMM nanocavity-enhanced photodetectors based on atomically thin TMDCs toward their implementation in the next-generation nanoscale optoelectronic devices and systems operating at the VIS-NIR-SWIR spectral regime.