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<jats:p>We explore the photoluminescence properties of zinc silicate (Zn<jats:sub>2</jats:sub>SiO<jats:sub>4</jats:sub>) nanostructures synthesized by vapor-liquid-solid (VLS) mode of growth using three different catalysts (Sn, Ag, and Mn). Different catalysts significantly influence the growth rate which in turn has an impact on the structure and hence the photoluminescence of the prepared zinc silicate nanostructures. Zn<jats:sub>2</jats:sub>SiO<jats:sub>4</jats:sub> has a wide bandgap of about 5.5 eV and in its pure form, it does not emit in visible region due to its inner shell electronic transitions between the 3d<jats:sup>5</jats:sup> energy levels. However, the incorporation of different catalysts (Sn, Ag and Mn) at different growth temperatures into the Zn<jats:sub>2</jats:sub>SiO<jats:sub>4</jats:sub> crystal growth kinetics provides wide visible spectral range of photoluminescence (PL) emissions. PL analysis shows broad multi-band spectrum in the visible region and distinct colors (red, yellow, green, blue, cyan and violet) are obtained depending on the crystalline structure of the prepared nanostructures. The allowed transitions due to the effect of different catalysts on zinc silicate lattice offer a huge cross-section of absorption that generates strong photoluminescence. The correlation between the structural and optical properties of the synthesized nanostructures is discussed in detail. The synthesized photoluminescent nanostructures have potential applications in solid-state lighting and display devices.</jats:p>

<jats:p>We theoretically study the near-field couplings of two stacked all-dielectric nanodisks, where each disk has an electric anapole mode consisting of an electric dipole mode and an electric toroidal dipole (ETD) mode. Strong bonding and anti-bonding hybridizations of the ETD modes of the two disks occur. The bonding hybridized ETD can interfere with the dimer’s electric dipole mode and induce a new electric anapole mode. The anti-bonding hybridization of the ETD modes can induce a magnetic toroidal dipole (MTD) response in the disk dimer. The MTD and magnetic dipole resonances of the dimer form a magnetic anapole mode. Thus, two dips associated with the hybridized modes appear on the scattering spectrum of the dimer. Furthermore, the MTD mode is also accompanied by an electric toroidal quadrupole mode. The hybridizations of the ETD and the induced higher-order modes can be adjusted by varying the geometries of the disks. The strong anapole mode couplings and the corresponding rich higher-order mode responses in simple all-dielectric nanostructures can provide new opportunities for nanoscale optical manipulations.</jats:p>

<jats:p>Monolayer transition metal dichalcogenides favor the formation of a variety of excitonic quasiparticles, and can serve as an ideal material for exploring room-temperature many-body effects in two-dimensional systems. Here, using mechanically exfoliated monolayer WS<jats:sub>2</jats:sub> and photoluminescence (PL) spectroscopy, exciton emission peaks are confirmed through temperature-dependent and electric-field-tuned PL spectroscopy. The dependence of exciton concentration on the excitation power density at room temperature is quantitatively analyzed. Exciton concentrations covering four orders of magnitude are divided into three stages. Within the low carrier concentration stage, the system is dominated by excitons, with a small fraction of trions and localized excitons. At the high carrier concentration stage, the localized exciton emission from defects coincides with the emission peak position of trions, resulting in broad spectral characteristics at room temperature.</jats:p>

<jats:p>Nickel-rich cathode materials are increasingly being applied in commercial lithium-ion batteries to realize higher specific capacity as well as improved energy density. However, low structural stability and rapid capacity decay at high voltage and temperature hinder their rapid large-scale application. Herein, a wet chemical method followed by a post-annealing process is utilized to realize the surface coating of tantalum oxide on LiNi<jats:sub>0.88</jats:sub>Mn<jats:sub>0.03</jats:sub>Co<jats:sub>0.09</jats:sub>O<jats:sub>2</jats:sub>, and the electrochemical performance is improved. The modified LiNi<jats:sub>0.88</jats:sub>Mn<jats:sub>0.03</jats:sub>Co<jats:sub>0.09</jats:sub>O<jats:sub>2</jats:sub> displays an initial discharge capacity of ∼ 233 mAh/g at 0.1 C and 174 mAh/g at 1 C after 150 cycles in the voltage range of 3.0 V–4.4 V at 45 °C, and it also exhibits an enhanced rate capability with 118 mAh/g at 5 C. The excellent performance is due to the introduction of tantalum oxide as a stable and functional layer to protect the surface of LiNi<jats:sub>0.88</jats:sub>Mn<jats:sub>0.03</jats:sub>Co<jats:sub>0.09</jats:sub>O<jats:sub>2</jats:sub>, and the surface side reactions and cation mixing are suppressed at the same time without hampering the charge transfer kinetics.</jats:p>

<jats:p>We develop a simple new design for a multi-band metamaterial absorber (MTMA) for radar applications. Computer Simulation Technology (CST) Studio Suite 2018 was used for the numerical analysis and absorption study. The simulated results show four high peaks at 5.6 GHz, 7.6 GHz, 10.98 GHz, and 11.29 GHz corresponding to absorption characteristics of 100%, 100%, 99%, and 99%, respectively. Furthermore, two different structures were designed and compared with the proposed MTMA. The proposed structure remained insensitive for any incident angle and polarization angle from 0° to 60°. Moreover, negative constitutive parameters were retrieved numerically. To support the simulated results, the proposed design was fabricated by using a computer numerical control-based printed circuit board prototyping machine and tested experimentally in a microwave laboratory. The absorption mechanism of the proposed MTMA is presented through the surface current and electric field distributions. The novelties of the proposed structure are a simple and new design, ease of fabrication, low cost, durability, suitability for real-time applications and long-term stability given the fabrication technique and non-destructive measurement method and very high absorption. The proposed structure has potential applications in C and X band frequency ranges.</jats:p>

<jats:p>A C-shaped pocket tunnel field effect transistor (CSP-TFET) has been designed and optimized based on the traditional double-gate TFETs by introducing a C-shaped pocket region between the source and channel to improve the device performance. A gate-to-pocket overlapping structure is also examined in the proposed CSP-TFET to enhance the gate controllability. The effects of the pocket length, pocket doping concentration and gate-to-pocket overlapping structure on the DC and analog/RF characteristics of the CSP-TFET are estimated after calibrating the tunneling model in double-gate TFETs. The DC and analog/RF performance such as on-state current (<jats:italic>I</jats:italic> <jats:sub>on</jats:sub>), on/off current ratio (<jats:italic>I</jats:italic> <jats:sub>on</jats:sub>/<jats:italic>I</jats:italic> <jats:sub>off</jats:sub>), subthreshold swing (<jats:italic>SS</jats:italic>) transconductance (<jats:italic>g</jats:italic> <jats:sub>m</jats:sub>), cut-off frequency (<jats:italic>f</jats:italic> <jats:sub>T</jats:sub>) and gain–bandwidth product (GBP) are investigated. The optimized CSPTFET device exhibits excellent performance with high <jats:italic>I</jats:italic> <jats:sub>on</jats:sub> (9.98 × 10<jats:sup>−4</jats:sup> A/μm), high <jats:italic>I</jats:italic> <jats:sub>on</jats:sub>/<jats:italic>I</jats:italic> <jats:sub>off</jats:sub> (∼ 10<jats:sup>11</jats:sup>), as well as low <jats:italic>SS</jats:italic> (∼ 12 mV/dec). The results reveal that the CSP-TFET device could be a potential alternative for the next generation of semiconductor devices.</jats:p>

<jats:p>By using the MOS-based model established in this paper, the physical process of photoelectron generation, transfer, and storage in the four-transistor active pixel sensor (4T-APS) pixels can be simulated in SPICE environment. The variable capacitance characteristics of double junctions in pinned photodiodes (PPDs) and the threshold voltage difference formed by channel nonuniform doping in transfer gates (TGs) are considered with this model. The charge transfer process of photogenerated electrons from PPDs to the floating diffusion (FD) is analyzed, and the function of nonuniform doping of TGs in suppressing charge injection back to PPDs is represented with the model. The optical and electrical characteristics of all devices in the pixel are effectively combined with the model. Moreover, the charge transfer efficiency and the voltage variation in PPD can be described with the model. Compared with the hybrid simulation in TCAD and the Verilog-A simulation in SPICE, this model has higher simulation efficiency and accuracy, respectively. The effectiveness of the MOS-based model is experimentally verified in a 3 μm test pixel designed in 0.11 μm CIS process.</jats:p>

<jats:p>Thermionic emission is a tunneling phenomenon, which depicts that electrons on the surface of a conductor can be pulled out into the vacuum when they are subjected to high electrical tensions while being heated hot enough to overtake their work functions. This principle has led to the great success of the so-called vacuum tubes in the early 20th century. To date, major challenges still remain in the miniaturization of a vacuum channel transistor for on-chip integration in modern solid-state integrated circuits. Here, by introducing nano-sized vacuum gaps (∼ 200 nm) in a van der Waals heterostructure, we successfully fabricated a one-dimensional (1D) edge-to-edge thermionic emission vacuum tube using graphene as the filament. With the increasing collector voltage, the emitted current exhibits a typical rectifying behavior, with the maximum emission current reaching 200 pA and an ON–OFF ratio of 10<jats:sup>3</jats:sup>. In addition, it is found that the maximum emission current is proportional to the number of the layers of graphene. Our results expand the research of nano-sized vacuum tubes to an unexplored physical limit of 1D edge-to-edge emission, and hold great promise for future nano-electronic systems based on it.</jats:p>

<jats:p>A GaN-based high electron mobility transistor (HEMT) with p-GaN islands buried layer (PIBL) for terahertz applications is proposed. The introduction of a p-GaN island redistributes the electric field in the gate–drain channel region, thereby promoting the formation of electronic domains in the two-dimensional electron gas (2DEG) channel. The formation and regulation mechanism of the electronic domains in the device are investigated using Silvaco-TCAD software. Simulation results show that the 0.2 μm gate HEMT with a PIBL structure having a p-GaN island doping concentration (<jats:italic>N</jats:italic> <jats:sub>p</jats:sub>) of 2.5 × 10<jats:sup>18</jats:sup> cm<jats:sup>−3</jats:sup>–3 × 10<jats:sup>18</jats:sup> cm<jats:sup>−3</jats:sup> can generate stable oscillations up to 344 GHz–400 GHz under the gate–source voltage (<jats:italic>V</jats:italic> <jats:sub>gs</jats:sub>) of 0.6 V. As the distance (<jats:italic>D</jats:italic> <jats:sub>p</jats:sub>) between the p-GaN island and the heterojunction interface increases from 5 nm to 15 nm, the fundamental frequency decreases from 377 GHz to 344 GHz, as well as the ratio of oscillation current amplitude of the fundamental component to the average component <jats:italic>I</jats:italic> <jats:sub>f</jats:sub>/<jats:italic>I</jats:italic> <jats:sub>avg</jats:sub> ranging from 2.4% to 3.84%.</jats:p>

<jats:p>Dual phase grating interferometer may simultaneously achieve large field of view and high x-ray dose efficiency. Here, we develop a simple theoretical method to better understand the imaging process of the dual phase grating interferometer. The derivation process of fringe period and the optimal visibility conditions of the dual phase grating interferometer are given in detail. Then, we theoretically prove that the fringe period and optimal visibility conditions of the dual phase grating interferometer include that of the Talbot interferometer. By comparing our experimental results with those of other researchers, we find that when the positions of phase gratings are far away from the positions where the fringe visibility is optimal, the fringe period of the dual <jats:italic>π</jats:italic>-phase grating interferometer is twice the theoretical results under the illumination of polychromatic x-ray. This conclusion may explain the contradictory research results of dual phase grating interferometer among different researchers.</jats:p>