Enhancement of MoTe₂ near-infrared absorption with gold hollow nanorods for photodetection

Infrared (IR) light photodetection based on two dimensional (2D) materials of proper bandgap has attracted increasing attention. However, the weak IR absorption in 2D materials, due to their ultrathin attribute and indirect bandgap in multilayer structures, degrades their performance when used as IR photodetectors. In this work, we utilize the fact that few-layer MoTe₂ flake has a near-IR (NIR) bandgap and demonstrate a ~ 60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface. Such gold hollow nanorods have distinct absorption peak located also at the NIR regime, therefore induces strong resonance, benefitting NIR absorption in MoTe₂, resulting in strong near-field enhancement. With the evidence from steady and transient state optical spectra, we confirm that the enhancement of NIR response originates only photon absorption, rather than electron transport at interfaces as observed in other heterostructures, therefore, precluding the requirement of high-quality interfaces for commercial applications.