This paper presents a new theoretical proposal for a surface plasmon resonance (SPR) terahertz metamaterial absorber with five narrow absorption peaks. The overall structure comprises a sandwich stack consisting of a gold bottom layer, a silica medium, and a single-layer patterned graphene array on top. COMSOL simulation represents that the five absorption peaks under TE polarization are at f_I = 1.99 THz (95.82%), f_Ⅱ = 6.00 THz (98.47%), f_Ⅲ = 7.37 THz (98.72%), f_Ⅳ = 8.47 THz (99.87%), and f_V = 9.38 THz (97.20%), respectively, which is almost consistent with the absorption performance under TM polarization. In contrast to noble metal absorbers, its absorption rates and resonance frequencies can be dynamically regulated by controlling the Fermi level and relaxation time of graphene. In addition, the device can maintain high absorptivity at 0~50° in TE polarization and 0~40° in TM polarization. The maximum refractive index sensitivity can reach S_V = 1.75 THz/RIU, and the maximum figure of merit (FOM) can reach FOM_V = 12.774 RIU⁻¹. In conclusion, our design has the properties of dynamic tunability, polarization independence, wide-incident-angle absorption, and fine refractive index sensitivity. We believe that the device has potential applications in photodetectors, active optoelectronic devices, sensors, and other related fields.

This article proposes a temperature-controlled absorber based on VO₂, which consists of five layers: a disk-shaped VO₂ layer array, a dielectric layer, a circular hole VO₂ array, a SiO₂ layer, and a gold substrate from top to bottom. We optimized the thickness of the other four layers of the absorber, except for the gold layer, using PSO. After ten iterations, we determined that the optimal parameters for the top-to-bottom four-layer thicknesses were 0.183 μm, 0.452 μm, 0.557 μm and 1.994 μm. At this point, our absorber reached the optimal absorption parameters, and we plotted the absorption spectrum under these conditions. We found that the absorption rate at 29.1–47.2 THz was higher than 90%, and the absorption bandwidth was as high as 18.1 THZ. This frequency band covers most of the atmospheric window area (23–37.5 THz), so it will have good practicality. At 30.8 THz and 43.12 THz, there were perfect absorption peaks with absorption rates of 99.99% and 99.99%, respectively. We explained the cause of absorption from the perspective of electric field, and then we studied the change in the absorption curve of the absorber when the temperature of VO₂ changed, and we can directly observe the changes in the electric field to explain this. Finally, we can tune the bandwidth and absorption rate of the absorber by changing the structure of the VO₂ pattern. After comparing with other absorbers developed in recent years, our absorber still has good competitiveness, and we believe that our solution is expected to have outstanding performance in fields such as photothermal conversion and thermal stealth in the future.

Indium tin oxide (ITO) has been studied for applications at normal high temperatures, below 600°C, due to its excellent electrical characteristics. In an attempt to further match the needs of electronics for use in extremely harsh environments, the changes in the conductive properties of ITO films and their mechanism were investigated at special high-temperatures above 1,000°C. ITO films were prepared by pulsed laser deposition (PLD) onto lanthanum gallium silicate (LGS) substrates. Furthermore, the as-deposited samples were annealed with different temperature-time treatments, and we investigated the effects of annealing on the electrical, structure, surface morphology and chemical properties of the ITO films by X-ray diffraction analysis, scanning electron microscopy (SEM), resistance measurements, and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the decreased resistance of the ITO films was mainly attributed to the increase in the crystalline size and the increased amount of Sn⁴⁺ ions during the heating period (0–1,000°C). Generally, the ITO films showed stable electrical properties when they were heated at 1,000°C for at least 2.5 h. As expected, the ITO films that remained steady above 1,000°C have potential applications as electrodes working in special high-temperature environments.

Reliability of nonvolatile resistive switching devices is the key point for practical applications of next-generation nonvolatile memories. Nowadays, nanostructured organic/inorganic heterojunction composites have gained wide attention due to their application potential in terms of large scalability and low-cost fabrication technique. In this study, the interaction between polyvinyl alcohol (PVA) and two-dimensional material molybdenum disulfide (MoS₂) with different mixing ratios was investigated. The result confirms that the optimal ratio of PVA:MoS₂ is 4:1, which presents an excellent resistive switching behavior. Moreover, we propose a resistive switching model of Ag/ZnO/PVA:MoS₂/ITO bilayer structure, which inserts the ZnO as the protective layer between the electrode and the composite film. Compared with the device without ZnO layer structure, the resistive switching performance of Ag/ZnO/PVA:MoS₂/ITO was improved greatly. Furthermore, a large resistive memory window up to 10⁴ was observed in the Ag/ZnO/PVA:MoS₂/ITO device, which enhanced at least three orders of magnitude more than the Ag/PVA:MoS₂/ITO device. The proposed nanostructured Ag/ZnO/PVA:MoS₂/ITO device has shown great application potential for the nonvolatile multilevel data storage memory.

The main development direction for current solar technology is to improve absorption efficiency and stability. To bridge this gap, we design in this paper a structure consisting of two multilayer disc stacks of different radii, one topped by a TiO₂ disc and the other by a cascade disc stack composed of SiO₂-Ti, for use in thermal emitters and solar absorbers. The innovation of our work is the exploitation of multiple Fabry–Perot resonances in SiO₂-Ti cascade optical cavities to develop absorber bandwidths while investigating it in the field of thermal emission and many aspects affecting the efficiency of the absorber. The finite difference time domain method (FDTD) results show absorption averages as high as 96.68% with an absorption bandwidth of 2445 nm (A > 90%) at 280 nm–3000 nm solar incidence and even higher weighted averages as high as 98.48% at 1.5 solar air mass (AM) illumination. In order to investigate the physical mechanisms of our designed absorber in a high absorption state, we analyzed the electric field distributions of its four absorption peaks and concluded that its high absorption is mainly caused by the coupling of multiple Fabry–Perot resonance modes in the cascaded optical cavity. While considering this high efficiency, we also investigated the effect of complex environments such as extreme high temperatures and changes in the angle of incidence of the absorber, and the results show that the thermal radiation efficiency of the emitter is 96.79% at an operating temperature of 1700 K, which is higher than its thermal radiation efficiency of 96.38% at an operating temperature of 1500 K, which is a perfect result. On the other hand, we conclude that the designed structure is independent of polarization, while the absorber still has 88.22% absorption at incidence angles of up to 60°, both in transverse electric (TE) and transverse magnetic (TM) modes. The results of this study can help improve the performance of future solar absorbers and expand their application areas.