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<jats:p>High-quality Fe-doped TiO<jats:sub>2</jats:sub> films are epitaxially grown on MgF<jats:sub>2</jats:sub> substrates by pulsed laser deposition. The x-ray diffraction and Raman spectra prove that they are of pure rutile phase. High-resolution transmission electron microscopy (TEM) further demonstrates that the epitaxial relationship between rutile-phased TiO<jats:sub>2</jats:sub> and MgF<jats:sub>2</jats:sub> substrates is 110 TiO<jats:sub>2</jats:sub> ∥ 110 MgF<jats:sub>2</jats:sub>. The room temperature ferromagnetism is detected by alternative gradient magnetometer. By increasing the ambient oxygen pressure, magnetization shows that it decreases monotonically while absorption edge shows a red shift. The transport property measurement demonstrates a strong correlation between magnetization and carrier concentration. The influence of ambient oxygen pressure on magnetization can be well explained by a modified bound magnetization polarization model.</jats:p>

<jats:p>Photonic-plasmonic hybrid microcavities, which possess a higher figure of merit <jats:italic>Q</jats:italic>/<jats:italic>V</jats:italic> (the ratio of quality factor to mode volume) than that of pure photonic microcavities or pure plasmonic nano-antennas, play key roles in enhancing light–matter interaction. In this review, we summarize the typical photonic-plasmonic hybrid microcavities, such as photonic crystal microcavities combined with plasmonic nano-antenna, whispering gallery mode microcavities combined with plasmonic nano-antenna, and Fabry–Perot microcavities with plasmonic nano-antenna. The physics and applications of each hybrid photonic-plasmonic system are illustrated. The recent developments of topological photonic crystal microcavities and topological hybrid nano-cavities are also introduced, which demonstrates that topological microcavities can provide a robust platform for the realization of nanophotonic devices. This review can bring comprehensive physical insights of the hybrid system, and reveal that the hybrid system is a good platform for realizing strong light–matter interaction.</jats:p>

<jats:p>The equivalent medium theory of metamaterials provides a way to obtain their effective constitutive parameters. However, because of its non-reciprocity, the complexity of the electromagnetic coupling, and a metallic bottom layer, it has been challenging to retrieve them from a metamaterial absorber. In this paper, we propose a method without any approximation to obtain them, in which the non-reciprocity and the strong electromagnetic coupling are included. Compared with the three methods such as symmetric metamaterial method, asymmetric metamaterial method and metasurface method, our method can reveal the metamaterial absorber’s electrical and magnetic resonance and show its electromagnetic coupling coefficients. To deal with a metamaterial absorber with a metallic bottom layer, four corners of the metallic bottom layer in the unit cell are removed, making it possible to retrieve the electromagnetic parameters. Surprisingly, these results show that the metamaterial absorber with a metallic bottom layer in our example operates in a negative refraction state at the half absorption frequencies, which helps further understand the absorbing mechanism of these metamaterial absorbers.</jats:p>

<jats:p>Thin films of millimeter-scale continuous monolayer WS<jats:sub>2</jats:sub> have been grown on SiO<jats:sub>2</jats:sub>/Si substrate, followed by the deposition of <jats:italic>β</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> crystals on monolayer WS<jats:sub>2</jats:sub> to prepare In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>/WS<jats:sub>2</jats:sub> van de Waals heterostructures by a two-step chemical vapor deposition (CVD) method. After the growth of In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> at elevated temperatures, high densities of In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>/WS<jats:sub>2</jats:sub> heterostructure bubbles with monolayer to multilayer <jats:italic>β</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub> crystals atop are observed. Fluorescence of the resultant <jats:italic>β</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>/WS<jats:sub>2</jats:sub> heterostructure is greatly enhanced in intensity upon the formation of bubbles, which are evidenced by the Newton’s rings in optical image owing to constructive and destructive interference. In photoluminescence (PL) mapping images of monolayer <jats:italic>β</jats:italic>-In<jats:sub>2</jats:sub>Se<jats:sub>3</jats:sub>/monolayer WS<jats:sub>2</jats:sub> heterobilayer bubble, significant oscillatory behavior of emission intensity is demonstrated due to constructive and destructive interference. However, oscillatory behaviors of peak position are also observed and come from a local heating effect induced by an excitation laser beam. The oscillatory mechanism of PL is further verified by changing the exterior pressure of bubbles placed in a home-made vacuum chamber. In addition, redshifted in peak position and broadening in peak width are observed due to strain effect during decreasing the exterior pressure of bubbles.</jats:p>

<jats:p>The effect of nitrogen flow and growth temperature on extension of GaN on Si substrate has been studied. By increasing the nitrogen flow whose outlet is located in the center of the MOCVD (metal–organic chemical vapor deposition) gas/particle screening flange and by increasing the growth temperature of HT-AlN and AlGaN buffer layers near the primary flat of the wafer, the GaN layer has extended more adequately on Si substrate. In the meantime, the surface morphology has been greatly improved. Both the AlN and GaN crystal quality uniformity has been improved. X-ray diffraction results showed that the GaN (0002) XRD FWHMs (full width at half maximum) decreased from 579 arcsec∼ 1655 arcsec to around 420 arcsec.</jats:p>

<jats:p>A new type of degradation phenomena featured with increased subthreshold swing and threshold voltage after negative gate bias stress (NBS) is observed for amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs), which can recover in a short time. After comparing with the degradation phenomena under negative bias illumination stress (NBIS), positive bias stress (PBS), and positive bias illumination stress (PBIS), degradation mechanisms under NBS is proposed to be the generation of singly charged oxygen vacancies (<jats:inline-formula> <jats:tex-math><?CDATA ${V}_{{\rm{o}}}^{+}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>V</mml:mi> <mml:mi mathvariant="normal">o</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_11_118102_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>) in addition to the commonly reported doubly charged oxygen vacancies (<jats:inline-formula> <jats:tex-math><?CDATA ${V}_{{\rm{o}}}^{2+}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>V</mml:mi> <mml:mi mathvariant="normal">o</mml:mi> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>+</mml:mo> </mml:mrow> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_11_118102_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>). Furthermore, the NBS degradation phenomena can only be observed when the transfer curves after NBS are measured from the negative gate bias to the positive gate bias direction due to the fast recovery of <jats:inline-formula> <jats:tex-math><?CDATA ${V}_{{\rm{o}}}^{+}$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>V</mml:mi> <mml:mi mathvariant="normal">o</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_30_11_118102_ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> under positive gate bias. The proposed degradation mechanisms are verified by TCAD simulation.</jats:p>

<jats:p>Hybrid halide perovskites have great potential for applications in optoelectronic devices. However, the typical ion migration in perovskite could lead to the non-repeatability of electrical measurement, instability of material, and degradation of device performance. The basic current–voltage behavior of perovskite materials is intricate due to the mixed electronic–ionic characteristic, which is still poorly understood in these semiconductors. Developing novel measurement schematic is a promising solution to obtain the intrinsic electrical performance without the interference of ion migration. Herein, we explore the pulse-voltage (PV) method on methylammonium lead tribromide single crystals to protect the device from the ion migration. A guideline is summarized through the analysis of measurement history and condition parameters. The influence of the ion migration on current–voltage measurement, such as repeatability and hysteresis loop, is under controlled. An application of the PV method is demonstrated on the activation energy of conductivity. The abruption of activation energy still exists near the phase transition temperature despite the ion migration is excluded by the PV method, introducing new physical insight on the current–voltage behavior of perovskite materials. The guideline on PV method will be beneficial for measuring halide perovskite materials and developing optoelectronic applications with new technique schematic.</jats:p>

<jats:p>Azo-based pillar[6]arene supramolecular organic frameworks are reported for CO<jats:sub>2</jats:sub> and N<jats:sub>2</jats:sub> adsorption and separation by density functional theory and grand canonical Monte–Carlo simulation. Azo-based pillar[6]arene provides suitable environment for CO<jats:sub>2</jats:sub> adsorption and selectivity. The adsorption and selectivity results show that introducing azo groups can effectively improve CO<jats:sub>2</jats:sub> adsorption and selectivity over N<jats:sub>2</jats:sub>, and both CO<jats:sub>2</jats:sub> adsorption and CO<jats:sub>2</jats:sub> selectivity over N<jats:sub>2</jats:sub> follow the sequence pillar[6]arene_N4 &gt; pillar[6]arene_N2 &gt; pillar[6]arene. Pillar[6]arene_N4 exhibits CO<jats:sub>2</jats:sub> adsorption capacity of ∼ 1.36 mmol/g, and superior selectivity of CO<jats:sub>2</jats:sub> over N<jats:sub>2</jats:sub> of ∼ 116.75 with equal molar fraction at 1 bar (1 bar = 10<jats:sup>5</jats:sup> Pa) and 298 K. Interaction analysis confirms that both the Coulomb and van der Waals interactions between CO<jats:sub>2</jats:sub> with pillar[6]arene frameworks are greater than that of N<jats:sub>2</jats:sub>. The stronger affinity of CO<jats:sub>2</jats:sub> with pillar[6]arene_N4 than other structures and the larger isosteric heat differences between CO<jats:sub>2</jats:sub> and N<jats:sub>2</jats:sub> rendered pillar[6]arene_N4 to present the high CO<jats:sub>2</jats:sub> adsorption capacity and high CO<jats:sub>2</jats:sub> selectivity over N<jats:sub>2</jats:sub>. Our results highlight the potential of azo-functionalization as an excellent means to improve pillar[6]arene for CO<jats:sub>2</jats:sub> capture and separation.</jats:p>

<jats:p>Pressure can reduce the distances among atoms, thereby modifying the overall optical characteristics of molecules. In this article, the excited state behavior of perylene is carefully observed under isotropic pressure and non-complexing condition. In a steady state, absorption peak shows red shift and spectral width are broadened with pressure increasing, which is ascribed to the <jats:italic>π</jats:italic>-electron delocalization between molecules. In a transient state, the transition dynamics presents a wavelike tendency with pressure increasing because the shift of self-tapping exciton state is contrary to that of <jats:italic>Y</jats:italic>-state with pressure increasing. The results conduce to understanding the influence of inter-molecule interaction on excited state behavior with inter-molecule distance decreasing, which contributes to studying the materials under extreme condition.</jats:p>

<jats:p>Unstable mechanical structure, low energy efficiency, and cooling requirements limit the application of conventional x-ray tubes based on filament as cathode in several academic areas. In this paper, we demonstrate a light-controlled pulsed x-ray tube using multialkali cathode as electron generator. The photocathode active area of the light controlled x-ray tube is 13.2 cm<jats:sup>2</jats:sup> (41 mm in diameter), which provides high photoelectron-emitting efficiency up to 0.288 mA/lm in 460-nm LED and 2.37-mA maximum tube current. Furthermore, the modulation ability from 1 kHz to 100 kHz of the x-ray tube is tested. The results suggest that the light-controlled pulsed x-ray tube has easy modulation and short x-ray pulse properties and is promising to be the next generation x-ray tube with wide applications in medical radiationtherapy as well as the calibration for detectors and scintillators.</jats:p>