Terahertz Absorptance in MoS₂/Graphene Nanoribbon Heterostructures

Terahertz (THz) frequency has promising applications in communication, security scanning, medical imaging, and food industry. As for the candidate materials to be used in THz applications, graphene has favorable electronic and optical properties, with plasmonic resonance frequency in the THz range. However, the small bandgap in this material can hinder the performance. There are ways to increase the bandgap of graphene through some techniques, one of them is making nanoribbon strips of graphene where the carrier confinement in the rib-bons induces a larger band gap. Besides, monolayer MoS2 has high transmittance in the THz range and a wider band gap, that can help enhance graphene absorption. In this work, using a computational model, we studied the absorption of infinite MoS2/graphene nanoribbons on SiO2 substrate in the THz range. The structure showed better absorption (at least twice) that of graphene-only nanoribbons. The absorption frequency can be easily tuned through the whole THz range by varying the vertical gate voltage. The absorption frequency is also affected by the nanoribbon width, and substrate thickness. The temperature, however, has little effect on shifting the absorption frequency, so the structure performance is found to be stable at different temperatures. The structure represents a cheap, easily fabricated, and tunable THz frequency absorber that can be used in many applications like sensing, cancer diagnosis and communication systems.