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<jats:p>A fluid model is employed to investigate the effect of radio frequency bias on the behavior of an argon inductively coupled plasma (ICP). In particular, the effects of ICP source power, single-frequency bias power, and dual-frequency bias power on the characteristics of ICP are simulated at a fixed pressure of 30 mTorr (1 Torr = 1.33322 × 10<jats:sup>2</jats:sup> Pa). When the bias frequency is fixed at 27.12 MHz, the two-dimensional (2D) plasma density profile is significantly affected by the bias power at low ICP source power (<jats:italic>e.g.</jats:italic>, 50 W), whereas it is weakly affected by the bias power at higher ICP source power (<jats:italic>e.g.</jats:italic>, 100 W). When dual-frequency (27.12 MHz/2.26 MHz) bias is applied and the sum of bias powers is fixed at 500 W, a pronounced increase in the maximum argon ion density is observed with the increase of the bias power ratio in the absence of ICP source power. As the ratio of 27.12-MHz/2.26-MHz bias power decreases from 500 W/0 W to 0 W/500 W with the ICP source power fixed at 50 W, the plasma density profiles smoothly shifts from edge-high to center-high, and the effect of bias power on the plasma distribution becomes weaker with the bias power ratio decreasing. Besides, the axial ion flux at the substrate surface is characterized by a maximum at the edge of the substrate. When the ICP source power is higher, the 2D plasma density profiles, as well as the spatiotemporal and radial distributions of ion flux at the substrate surface are characterized by a peak in the reactor center, and the distributions of plasma parameters are negligibly affected by the dual-frequency bias power ratio.</jats:p>

<jats:p>We present the behaviors of both dynamical and static charge susceptibilities of doped armchair nanotubes using the Green function approach in the context of Holstein-model Hamiltonian. Specially, the effects of magnetization and gap parameter on the the plasmon modes of armchair nanotube are investigated via calculating correlation function of charge density operators. Random phase approximation has been implemented to find the interacting dynamical charge susceptibility. The electrons in this systems interacts with each other by mediation of dispersionless Holstein phonons. Our results show that the increase of gap parameter leads to decreasing intensity of charge collective mode. Also the frequency position of the collective mode tends to higher frequencies due to the gap parameter. Furthermore the number of collective excitation mode decreases with chemical potential in the presence of electron–phonon interaction. Finally the temperature dependence of static charge structure factor of armchair nanotubes is studied. The effects of the gap parameter, magnetization and electron–phonon interaction on the static structure factor are addressed in details.</jats:p>

<jats:p>HfAlO/InAlAs metal–oxide–semiconductor capacitor (MOS capacitor) is considered as the most popular candidate of the isolated gate of InAs/AlSb high electron mobility transistor (HEMT). In order to improve the performance of the HfAlO/InAlAs MOS-capacitor, samples are annealed at different temperatures for investigating the HfAlO/InAlAs interfacial characyeristics and the device’s electrical characteristics. We find that as annealing temperature increases from 280 °C to 480 °C, the surface roughness on the oxide layer is improved. A maximum equivalent dielectric constant of 8.47, a minimum equivalent oxide thickness of 5.53 nm, and a small threshold voltage of –1.05 V are detected when being annealed at 380 °C; furthermore, a low interfacial state density is yielded at 380 °C, and this can effectively reduce the device leakage current density to a significantly low value of 1 × 10<jats:sup>−7</jats:sup> A/cm<jats:sup>2</jats:sup> at 3-V bias voltage. Therefore, we hold that 380 °C is the best compromised annealing temperature to ensure that the device performance is improved effectively. This study provides a reliable conceptual basis for preparing and applying HfAlO/InAlAs MOS-capacitor as the isolated gate on InAs/AlSb HEMT devices.</jats:p>

<jats:p>Group-V elemental nanofilms were predicted to exhibit interesting physical properties such as nontrivial topological properties due to their strong spin–orbit coupling, the quantum confinement, and surface effect. It was reported that the ultrathin Sb nanofilms can undergo a series of topological transitions as a function of the film thickness <jats:italic>h</jats:italic>: from a topological semimetal (<jats:italic>h</jats:italic> &gt; 7.8 nm) to a topological insulator (7.8 nm &gt; <jats:italic>h</jats:italic> &gt; 2.7 nm), then a quantum spin Hall (QSH) phase (2.7 nm &gt; <jats:italic>h</jats:italic> &gt; 1.0 nm) and a topological trivial semiconductor (<jats:italic>h</jats:italic> &gt; 1.0 nm). Here, we report a comprehensive investigation on the epitaxial growth of Sb nanofilms on highly oriented pyrolytic graphite (HOPG) substrate and the controllable thermal desorption to achieve their specific thickness. The morphology, thickness, atomic structure, and thermal-strain effect of the Sb nanofilms were characterized by a combination study of scanning electron microscopy (SEM), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The realization of Sb nanofilms with specific thickness paves the way for the further exploring their thickness-dependent topological phase transitions and exotic physical properties.</jats:p>

<jats:p>We investigate structural, mechanical, thermodynamic, and thermoelectric properties of vanadium-based <jats:italic>X</jats:italic>VO<jats:sub>3</jats:sub> (<jats:italic>X</jats:italic> = Na, K, Rb) materials using density functional theory (DFT) based calculations. The structural and thermodynamic stabilities are probed by the tolerance factor (0.98, 1.01, and 1.02) with the negative value of enthalpy of formation. Mechanical properties are analyzed in the form of Born stability criteria, ductile/brittle nature (Poisson and Pugh’s ratios) and anisotropy factor. To explore the electronic transport properties, we study the electrical conductivity, thermal conductivity, Seebeck coefficient and power factor in terms of chemical potential and temperature. High values of Seebeck coefficient at room temperature may find the potential of the studied perovskites in thermo-electrics devices.</jats:p>

<jats:p>We report observation of dispersion for coupled exciton-polariton in a plate microcavity combining with ZnO/MgZnO multi-quantum well (QW) at room temperature. Benefited from the large exciton binding energy and giant oscillator strength, the room-temperature Rabi splitting energy can be enhanced to be as large as 60 meV. The results of excitonic polariton dispersion can be well described using the coupling wave model. It is demonstrated that mode modification between polariton branches allowing, just by controlling the pumping location, to tune the photonic fraction in the different detuning can be investigated comprehensively. Our results present a direct observation of the exciton-polariton dispersions based on two-dimensional oxide semiconductor quantum wells, thus provide a feasible road for coupling of exciton with photon and pave the way for realizing novel polariton-type optoelectronic devices.</jats:p>

<jats:p>The <jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> p–n heterojunctions (HJ) have been demonstrated using typical p-type oxide semiconductors (NiO or SnO). The <jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> thin film was heteroepitaxial grown by metal organic chemical vapor deposition (MOCVD) with three-step growth method. The polycrystalline SnO and NiO thin films were deposited on the <jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> thin film by electron-beam evaporation and thermal oxidation, respectively. The valence band offsets (VBO) were determined by x-ray photoelectron spectroscopy (XPS) to be 2.17 eV at SnO/<jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> and 1.7 eV at NiO/<jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>. Considering the bandgaps determined by ultraviolet-visible spectroscopy, the conduction band offsets (CBO) of 0.11 eV at SnO/<jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> and 0.44 eV at NiO/<jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> were obtained. The type-II band diagrams have been drawn for both p–n HJs. The results are useful to understand the electronic structures at the <jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> p–n HJ interface, and design optoelectronic devices based on <jats:italic>ε</jats:italic>-Ga<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> with novel functionality and improved performance.</jats:p>

<jats:p>Two-dimensional topological insulators (2DTIs) have attracted increasing attention during the past few years. New 2DTIs with increasing larger spin–orbit coupling (SOC) gaps have been predicted by theoretical calculations and some of them have been synthesized experimentally. In this review, the 2DTIs, ranging from single element graphene-like materials to bi-elemental transition metal chalcogenides (TMDs) and to multi-elemental materials, with different thicknesses, structures, and phases, have been summarized and discussed. The topological properties (especially the quantum spin Hall effect and Dirac fermion feature) and potential applications have been summarized. This review also points out the challenge and opportunities for future 2DTI study, especially on the device applications based on the topological properties.</jats:p>

<jats:p>We investigate the enhanced chirality of chiral molecular J-aggregates (TDBC) by the propagating surface plasmons (PSPs) in the metallic hole array structure filled with TDBC. The two ends of the hole in the metal film form a low quality factor Fabry–Perot (FP) cavity, and this cavity confines PSPs. The resonant wavelength of the metallic hole array is tuned by the lattice constant and the size of the hole. Both the resonant wavelength of Ag hole array and the volume ratio of TDBC in the hybridized structure influence on the enhancement of the circular dichroism (CD) spectrum. The curve of CD spectrum shows Fano-like line-shape, due to the interaction between the non-radiative field in the FP cavity and the radiative field in chiral TDBC. The maximum of the CD spectrum of the hybridized structure is 0.025 times as the one of the extinction spectrum in a certain structure, while the maximum of the CD spectrum of TDBC is 1/3000 times as the one of the extinction spectrum. The enhanced factor is about 75. The resonant wavelength of the metallic hole array can be tuned in a large wavelength regime, and the chirality of a series of molecular J-aggregates with different resonant wavelengths can be enhanced. Our structure provides a new method to amplify the chirality of molecular J-aggregates in experiments.</jats:p>

<jats:p>We theoretically study the Josephson effect in a quantum anomalous Hall insulator (QAHI) nanoribbon with a domain wall structure and covered by the superconductor. The anomalous Josephson current, the nonzero supercurrent at the zero superconducting phase difference, appears with the nonzero magnetization and the suitable azimuth angle of the domain wall. Dependent on the configuration of the domain wall, the anomalous current peaks in the Bloch type but disappears in the Néel type because the <jats:italic>y</jats:italic>-component of magnetization is necessary to break symmetry to arouse the anomalous current. The phase shift of the anomalous current is tunable by the magnetization, the azimuth angle, or the thickness of the domain wall. By introducing a bare QAHI region in the middle of the junction which is not covered by the superconductor, the anomalous Josephson effect is enhanced such that the phase shift can exceed <jats:italic>π</jats:italic>. Thus, a continuous change between 0 and <jats:italic>π</jats:italic> junctions is realized via regulating the configuration of the domain wall or the magnetization strength. As long as an s-wave superconductor is placed on the top of the QAHI with a domain wall structure, this proposal can be experimentally fabricated and useful for the phase battery or superconducting quantum bit.</jats:p>