Terahertz Modulation Properties Based on ReS₂/Si Heterojunction Films

Abstract

Low cost, low power consumption and high performance are urgent needs for the application of terahertz modulation devices in the 6G field. Rhenium disulfide (ReS2) is one of the ideal candidate materials due to its unique direct band gap, but it lacks in-depth research. In this work, a highly stable ReS2 nanodispersion was prepared by liquid-phase exfoliation, and a uniform, dense and well-crystallized ReS2 film was prepared on high-resistivity silicon by drop casting. The morphological, optical and structural properties of the ReS2/Si heterojunction film were characterized by OM, SEM, AFM, XRD, RS and PL. The terahertz performance was tested by using a homemade THz-TDS instrument, and the influence of different laser wavelengths and powers on the terahertz modulation performance of the sample was analyzed. The modulation depth of the sample was calculated based on the transmission curve, and the changes in the refractive index and conductivity of the sample with frequency at the corresponding laser power were calculated. The results show that the fabricated ReS2/Si heterojunction terahertz modulator can stably achieve 30% broadband modulation in the range of 0.3~1.5 THz under the low-power pumping of 1555 mW/cm2, and the maximum conductivity is 3.8 Ω−1m−1.

Keywords

• transition metal sulfide
• ReS_2/Si heterojunction films
• terahertz
• ultrafast characteristics
• optical parameters