Papers by Keyword: Heterostructure

Abstract: High-entropy alloys (HEAs), owing to their exceptionally favourable strength–ductility balance, are regarded as promising candidates for applications in the energy, automotive, and aerospace industries. A defining characteristic of face-centered cubic (FCC) high-entropy alloys is their low stacking fault energy, which facilitates deformation via mechanical twinning and promotes the activation of transformation-induced plasticity (TRIP) and twinning-induced plasticity (TWIP) mechanisms. The present study focuses on the development of a heterostructured material composed of CoNiFeMn and (CoNiFeMn)₉₅Mo₅ alloys. Furthermore, the Erichsen cupping test was performed to assess the formability of the produced material and to evaluate its suitability for deep drawing applications.

Abstract: Heterostructures are important for various electrical, optical, and magneto-transport applications. In the present work, MoS₂/ZnO heterostructures are successfully grown by magnetron sputtering followed by annealing of ZnO thin films. After annealing, ZnO is again coated with Mo by using the same technique. ZnO-Mo stack is further sulfurized to convert Mo into MoS₂. X-ray diffraction (XRD) showed the structural analysis of ZnO, MoS_2, and MoS₂/ZnO heterostructures with polycrystalline nature. Scanning electron microscopy (SEM) also supports the granular morphology of ZnO, MoS_2, and MoS₂/ZnO films. Energy dispersive X-ray analysis (EDX) confirms the presence of necessary elements i.e., Zn, Mo, S, O, and Si. Further, the impact of the magnetic field on the current-voltage (I-V) behavior of MoS₂/ZnO heterostructures, reveals insights into their magneto-resistive capabilities.

Abstract: Global energy consumption is increasingly becoming high due to industrial activity and advances both in developed and developing countries. Fossil fuels such as coal, natural gas, and oil are used to meet the energy demands all over the world. However, there is a concern about depletion of these resources and rise in greenhouse gas such as carbon dioxide emissions. Therefore, some alternative ways are needed to satisfy the energy demand and decrease the greenhouse emissions. Renewable energy, such as solar energy, wind energy, hydropower, and so on, is a promising source to satisfy the future energy requirements. As to solar cells, there is no need to concern about energy source because it uses solar rays, and it never emits CO₂ when generating electricity.

Abstract: ZIF-67@Ta₂O₅ graded hetero-structure material was designed and prepared using F-Ta₂O₅ as a raw material and Zeolite imidazole ester(ZIF-67) as framework structure material. The hetero-structure Ta₂O₅ and ZIF-67@Ta₂O₅ were annealing 6 hours at 900°C in nitrogen ambience. The photolysis properties of the Ta₂O₅ and ZIF-67@Ta₂O₅ materials as catalysts for photocatalytic decomposition of water to hydrogen were characterized. The results show that the heterogeneous composite structure formed by cobalt-tantalum oxide and tantalum pentoxide can significantly improve the hydrogen production performance of tantalum pentoxide samples, and the properties of samples obtained under nitrogen atmosphere are better. Among them, the N-50 sample (F-Ta₂O₅ is 50mg, Cobalt nitrate dosage is 6ml, annealing 6 hours at 900°C in nitrogen ambience) has the best hydrogen production performance, and the hydrogen production rate is 116μmol/g/h.

Abstract: Heterostructure thin films of indium and zinc oxides (IZO) were prepared by spray pyrolysis from an aqueous solution of the precursors at different substrate temperatures (T_S). The polycrystalline structure of bixbyite appeared at a low temperature. The crystallinity was enhanced with the emergence of the zinc oxide phase. By increasing the T_S to 623 K, the crystallite size was increased. SEM images reveal that the deposited sample at 523 K is composed of irregularly shaped nanoparticles with a lack of links. Increasing the T_S to 573 K increases the average particle diameters, and the particles appeared as polyhedrons well connected with cavities between them, which candidates for gas sensing applications. Increasing T_S to 623 K resulted in the particles merging. NO₂ gas sensor results confirmed the enhancement of IZO sensitivity performance at 573 K. Keywords: Gas sensor, thin film metal oxide, spray pyrolysis, In₂O₃– ZnO

Abstract: The development of next generation Li ion battery has attracted many attentions of researchers due to the rapidly increasing demands to portable energy storage devices. General Li metal/alloy anodes are confronted with challenges of dendritic crystal formation and slow charge/discharge rate. Recently, the prosperity of two-dimensional materials opens a new window for the design of battery anode. In the present study, MoS₂/graphene heterostructure is investigate for the anode application of Li ion battery using first-principles calculations. The Li binding energy, open-circuit voltage, and electronic band structures are acquired for various Li concentrations. We found the open-circuit voltage decreases from ~2.28 to ~0.4 V for concentration from 0 to 1. Density of states show the electrical conductivity of the intercalated heterostructures can be significantly enhanced. The charge density differences are used to explain the variations of voltage and density of states. Last, ~0.43 eV diffusion energy barrier of Li implies the possible fast charge/discharge rate. Our study indicate MoS₂/graphene heterostructure is promising material as Li ion battery anode.

Abstract: The design and technological conditions for the manufacture of photoconductive antennas based on low-temperature gallium arsenide (LT-GaAs) have been developed. The optimized photoconductive THz antenna is made based on LT-GaAs with the flag geometry of the contacts and with the interdigitated structure including metal closing through the dielectric of each second period. LT-GaAs samples were obtained by molecular beam epitaxy at temperatures of 210 °C, 230 °C, 240 °C on GaAs substrates (100). Dark and photocurrent were measured depending on the bias voltage of the LT-GaAs heterostructure at the EP6 probe station. Full wave finite element method solver has been used to investigate the proposed plasmon PCA electrical and optical behavior by combining the Maxwell's wave equation with the drift-diffusion/Poisson equations.

Abstract: It was found that at room temperature the value of the photoinduced current of Schottky diodes based on heterostructures InP/GaInAs/Pd at a hydrogen concentration of 0.03% is reduced by two orders of magnitude compared to the value without hydrogen. The value of the photoinduced current depends on the thickness of the depleted region on the surface of the semiconductor. A small change in the charged layer of H⁺ can cause a significant change in the thickness of this region and as a result, a strong change in the photoinduced current. This effect on current is much stronger than the influence of hydrogen concentration or capacitance without optical activation. As a result, it becomes possible to create hydrogen and hydrogen-containing gas sensors with much better sensitivity at room temperature. The original design of a miniature H₂ sensor including an IR LED, a Schottky diode with a Pd contact, a Peltier cooler and a thermosensor is demonstrated.

Abstract: In this work, we studied the ZnO film thickness effect on the photocatalytic performance of n-ZnO/p-NiO heterostructures. The ZnO and NiO films were prepared by sol-gel dip-coating technique and the thickness of the ZnO film was varied by changing the number of coatingsfrom 2 to12. The formation of the p-NiO/n-ZnO heterostructure was confirmed by X ray diffraction (XRD). The obtained ZnO films present a wurtzite structure with a preferred orientation along (002) direction while the NiO film present a cubic structure highly oriented along (200) direction. UV-visible transmittance spectra of the prepared heterostructures revealed a good transparency in the visible region. The photocatalytic propertiesof the n-ZnO/p-NiO heterostructures were investigated by measuring the degradation rate of methylene blue. All the samples exhibit a good photocatalytic activity under solar light irradiation. The photocatalytic activity of p-NiO/n-ZnO heterostructureswas strongly correlated with the number of ZnO coatings. The highest photocatalytic activity was obtained at 6 coatings with a degradation rate of methylene blue equal to 98.67% for 4.5h of irradiation.

Abstract: The paper presents the route of manufacturing transistors on gallium nitride. As a result of the work done, prototypes of transistor crystals with a gate length and width of 0.5 μm and 0.8 mm, respectively. The basic static characteristics are presented.