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In this article, novel sandwich-structured surface plasmon ultraviolet (UV) photodetectors based on ZnO thin films with engineered rear metal electrode were fabricated by radio-frequency magnetron sputtering. An exhaustive study about the impact of a dissimilar metallic layer (Au and Pt) on the structural, optical, and electrical properties of the device was carried out. The carrier collection property of the sandwich structure devices has the advantages of horizontal and vertical joint collection. In theory, adding a new metal semiconductor layer introduces a contact area and increases the resistance. An ultra-low dark noise current of less than 2.0 × 10–7 A and a responsivity exceeding 1.6 A/W were achieved with the prepared ZnO-based UV-PDs in the rear metallic electrode mode. The devices based on the ZnO/Pt/ZnO and MgZnO/Pt/MgZnO sandwich structures show high responsivity and fast response. This study provides a depletion layer width method for the fabrication of high-response UV photodetectors for surface plasmon-based materials by integrating metal semiconductor nanostructures. A homogeneous two-layer UV photodetector is constructed, which changes the traditional single-layer device structure and overcomes drawbacks of the single device structure.

The responsivity of surface plasmon (SP) modified metal–semiconductor-metal ultraviolet photodetectors (PDs) was increased from 1.15 × 10−3 to 2.5 × 10−3 A/W by varying the number of interdigitated electrode pairs. MgZnO films with Pt nanoparticles (NPs) having a grain size of 6.26 nm in a 25-pair interdigitated electrode arrangement showed improved responsivity and signal to noise ratio in comparison with the bare MgZnO PD. This improvement was attributed to both the enhanced conductivity and increased absorption resulting from the near-field enhancement of the SP. Parallel effect physical simulation results were in reasonable agreement with our experimental results.

Silicene-based materials have attracted great attention due to their easier incorporation into silicon-based devices and components. In addition to the reported hydrogenated 2D tetragonal silicene (γ-SiH), we propose two stable atomic configurations of hydrogenated 2D tetragonal silicene (α-SiH and β-SiH) based on first-principles calculation. The calculated results indicate hydrogenation can effectively open the band gap of 2D tetragonal silicene, α-SiH is a semiconductor with a direct band gap of 2.436 eV whereas β-SiH is indirect band gap of 2.286 eV. We also find that the electronic band structure of α-SiH, β-SiH and γ-SiH can be modulated via biaxial strain. By applying biaxial strain in the range of −10% to 12%, the band gap of α-SiH, β-SiH and γ-SiH can be tuned in a range of 1.732–2.585 eV. Furthermore, direct–indirect or indirect–direct transition can be induced under biaxial strain, showing a high degree of flexibility in electronic band structure. The research not only broadens the diversity of hydrogenated 2D tetragonal silicenes, but also provides more possibilities of their applications in spintronic devices.

In this work, dual-wavelength UV photodetectors were successfully constructed by growing ZnO and MgZnO layers on SiO2 substrates with ZnO/Au/MgZnO structure. The photodetectors exhibited high performance and the influence of different thickness of MgZnO layers was investigated. Moreover, simply by adjusting the applied voltage on the devices, the ratio of the two response peaks (caused by MgZnO and ZnO layers) changed therewith. The detecting properties may originate from the two layers having different increasing rates where the existence of Schottky junctions plays an important role. The photodetectors are meaningful for fabricating dual-wavelength optoelectronic devices for practical applications.

We proposed and demonstrated MgZnO metal-semiconductor-metal (MSM) ultraviolet photodetectors (UV) assisted with surface plasmons (SPs) prepared by the radio frequency magnetron sputtering deposition method. After the decoration of their surface with Pt nanoparticles (NPs), the responsivity of all the electrode spacing (3, 5, and 8 μm) photodetectors were enhanced dramatically; to our surprise, comparing with them the responsivity of larger spacing sample, more SPs were gathered which are smaller than others in turn. A physical mechanism focused on SPs and depletion width is given to explain the above results.

In this work, the responsivity-controlled high performance UV photodetectors fabricated from MgZnO films was investigated with an emphasis on the effect of varying the number of interdigitated electrode pairs. The responsivity of MgZnO photodetectors was optimized by increasing the number of interdigital electrode pairs at a given bias. The result is due to the parallel structure of the interdigital electrodes and the depletion width of the Schottky junctions. This demonstrates a straightforward way of tailoring the responsivity of UV photodetectors for practical applications.

Ferromagnetic (FM) materials with high Curie temperature, large spin polarization ratio and large perpendicular magnetic anisotropic (PMA) are the basis of constructing practical spintronic devices. Using first-principles calculations, electronic property, magnetism and magnetic anisotropic energy (MAE) of penta-MnN2 monolayer are investigated. The calculated results indicate that penta-MnN2 monolayer is FM half-metal and exhibits PMA. The PMA is induced by Mn atom of 0.207 meV/Mn, which is one or two orders of magnitude larger than those of bulk Co (−65 μeV/atom), Fe (−1.4 μeV/atom) and Ni (2.7 μeV/atom). It is worth noting that the structure, magnetism and MAE of penta-MnN2 monolayer can be manipulated by applying biaxial strain. By applying tensile strain of 3%, penta-MnN2 monolayer has a second energy minimum and remains the original crystalline symmetry, but the N–N bond length has a sudden change. The MAE of Mn atom in penta-MnN2 monolayer can be enhanced by 21% with compressive strain compared to the unstrained systems. Meanwhile, the MAE decreases with the increase of tensile strain, and it exhibits a more significant decrease due to the sudden drop of N–N bond with tensile strain. These results may broaden the development of two-dimensional (2D) FM materials, which have potential applications in 2D spintronic nanodevices.

Based on first-principles calculations, we systematically investigate the stability, structural and electronic properties of two-dimensional (2D) hydrogenated tetragonal stanene (tetra-SnH). The calculated binding and formation energies, AIMD simulations and phonon dispersion show 2D tetra-SnH is stable. The hydrogenation also affects the electronic structure of tetragonal stanene monolayer, which is transformed from semimetal to semiconductor with a direct band gap. The optical response of 2D tetra-SnH is isotropic along the in-plane directions. Our results demonstrate that hydrogenation is an efficient way to modulate the electronic properties of tetragonal stanene, and provides a new prospect for the potential application in nanoelectronics.

We report on metal-semiconductor-metal ultraviolet photodetectors based on a ZnO film/Pt nanoparticles/ZnO film composite structure. The responsivity of the sandwich photodetector is 45 times greater for the back-illuminated than the front-illuminated. Surprisingly, the responsivity of a ZnO photodetector without the Pt nanoparticles has rather feeble enhancement under the same conditions (illumination from back and front). The responsivity of the sandwich photodetector can be enhanced from 14 to 45 times by adjusting the embedded depth of the Pt nanoparticles. Combining this result with the optical absorption spectra of ZnO films with and without Pt nanoparticles, we can reasonable to deduce the underlying mechanism and attribute it to the coupling of the localized surface plasmon from Pt nanoparticles with ZnO films. These results demonstrate a method to control the responsivity enhancement by adjusting the embedded depth of the Pt nanoparticles in the sandwich photodetector.

Based on the ZnO/Pt nanoparticles/ZnO multilayer films by magnetron sputtering method, we elaborate the ultraviolet (UV) photodetectors and deduce that they provide an ideal platform for highly using efficient surface plasmon (SP) modes. By only adjusting the thickness of the top layer and remaining other conditions unchanged, we draw a conclusion that the responsivity of the sandwich photodetector can be drastically increased from 0.08 to 0.40 A/W. It firmly provides for our findings that the responsivity enhancement factors without Pt nanoparticles (NPs) are apparently smaller than those by means of introducing Pt NPs. This can be ascribed to the SP of Pt NPs. The near-field effect of SP results in the dependence of the responsivity enhancement of ZnO films on the top layer film thickness. Which are in good agreement with theoretical calculations.

A series of ultraviolet photodetectors have been fabricated on MgZnO films, the molar ratio of Mg/Zn is about 18%, which grown by a radio frequency magnetron sputtering technique. Metal (Pt) nanoparticles are sputtered on the surface of the MgZnO film, embedded into the film and deposited on the substrate to improve the performances of the photodetectors, respectively. I–V characteristics under dark are improved by sputtering Pt nanoparticles on the surface of MgZnO film. Meanwhile, the photoresponse of the photodetectors with Pt nanoparticles are enhanced, especially when nanoparticles embedded into the MgZnO film, the peak responsivity is enhanced from 0.134 to 0.349 A/W at 30 V bias. It is demonstrated that the key role of Pt nanoparticles in the performance enhancement of MgZnO-based photodetectors, revealing the applicability of metal nanoparticles in ultraviolet photodetectors.