Modulation of graphene THz absorption based on HAuCl4 doping method

Graphene nanospacer layer modulated multilayer composite structures of precious metals and their SERS performance

Graphene(G)-noble metal-ZnO hybrid systems were developed as highly sensitive and recyclable surface enhanced Raman scattering (SERS) platforms, in which ultrathin graphene of varying thickness was embedded between two metallic layers on top of a ZnO layer. Due to the multi-dimensional plasmonic coupling effect, the Au/G/Ag@ZnO multilayer structure possessed ultrahigh sensitivity with the detection limit of Rhodamine 6 G (R6G) as low as 1.0×10-13 mol/L and a high enhancement factor of 5.68×107. Both experimental and simulation results showed that graphene films could significantly regulate the interlayer plasmon resonance coupling strength, and single-layer graphene had the best interlayer regulation effect. Additionally, the SERS substrate structure prepared through physical methods exhibited high uniformity, the graphene component of the substrate possessed excellent molecular enrichment ability and silver oxidation inhibition characteristics, resulting in a substrate with high stability and exceptional reproducibility. The signal change was less than 15%. Simultaneously, due to the excellent photocatalytic performance of the low-cost and wide-band-gap semiconductor material ZnO, the SERS substrate exhibited exceptional reusability. Even after five cycles of adsorption-desorption, the SERS performance remained stable and maintained a reliable detection limit. The study introduced a novel approach to creating multilayer composite SERS substrates that exhibited exceptional performance, offering a new analytical tool with high sensitivity, stability, and reusability.

Multilayer graphene-enabled structure based on Salisbury shielding effect for high-performance terahertz absorption

Sandwich-type structure based on Salisbury screen effect is a simple and effective strategy to acquire high-performance terahertz (THz) absorption. The number of sandwich layer is the key factor that affects the absorption bandwidth and intensity of THz wave. Traditional metal/insulant/metal (M/I/M) absorber is difficult to construct multilayer structure because of low light transmittance of the surface metal film. Graphene exhibits huge advantages including broadband light absorption, low sheet resistance and high optical transparency, which are useful for high-quality THz absorber. In this work, we proposed a series of multilayer metal/PI/graphene (M/PI/G) absorber based on graphene Salisbury shielding. Numerical simulation and experimental demonstration were provided to explain the mechanism of graphene as resistive film for strong electric field. And it is important to improve the overall absorption performance of the absorber. In addition, the number of resonance peaks is found to increase by increasing the thickness of the dielectric layer in this experiment. The absorption broadband of our device is around 160%, greater than those previously reported THz absorber. Finally, this experiment successfully prepared the absorber on a polyethylene terephthalate (PET) substrate. The absorber has high practical feasibility and can be easily integrated with the semiconductor technology to make high efficient THz-oriented devices.