Enhancing Broad\nBand Photoresponse of 2D Transition-Metal\nDichalcogenide Materials Integrated with Hyperbolic Metamaterial Nanocavities

Transition-metal dichalcogenides (TMDCs) are becoming\nan important\nmaterial platform for constructing atomically thin optoelectronic\ndevices, mostly due to their direct-to-indirect band gap tunability\ndepending on their thickness and their ease of integration with various\nmaterial platforms. One of the most challenging applications of TMDCs\nis their utilization as efficient photodetectors, mostly due to their\nnanoscale thickness, which limits their light absorption. To enhance\nthe photodetection capabilities of TMDCs, one needs to adopt schemes\nfor light–matter interaction enhancement. In this regard, the\nplatform of hyperbolic metamaterial (HMM) nanocavities with indefinite\ndispersion and localized electromagnetic fields holds a great promise\nto enhance light–matter interactions. Motivated by the need\nfor improving the performance of atomically thin photodetectors and\nconsidering the capabilities of HMMs, we hereby demonstrate a broadband\nphotodetector with enhanced absorption based on the integration of\nTMDs with HMMs. Specifically, we have designed, fabricated, and experimentally\ncharacterized on-resonance and off-resonance photodetectors using\na few layers of MoTe<sub>2</sub> and MoS<sub>2</sub>, respectively.\nOverall, we observed an 8-fold (on-resonance) and 2.5-fold (off-resonance)\nenhancement of the photocurrent due to a localized electric field\naround each nanocavity. This enhancement of the localized electric\nfield is also verified by full wave finite difference time domain\nsimulations. The demonstrated photodetector approach provides an efficient\nstrategy for designing ultrathin HMM nanocavity-enhanced photodetectors\nbased on atomically thin TMDCs toward their implementation in the\nnext-generation nanoscale optoelectronic devices and systems operating\nat the VIS–NIR–SWIR spectral regime.