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<jats:p>The effects of dry O<jats:sub>2</jats:sub> post oxidation annealing (POA) at different temperatures on SiC/SiO<jats:sub>2</jats:sub> stacks are comparatively studied in this paper. The results show interface trap density (<jats:italic>D</jats:italic> <jats:sub>it</jats:sub>) of SiC/SiO<jats:sub>2</jats:sub> stacks, leakage current density (<jats:italic>J</jats:italic> <jats:sub>g</jats:sub>), and time-dependent dielectric breakdown (TDDB) characteristics of the oxide, are affected by POA temperature and are closely correlated. Specifically, <jats:italic>D</jats:italic> <jats:sub>it</jats:sub>, <jats:italic>J</jats:italic> <jats:sub>g</jats:sub>, and inverse median lifetime of TDDB have the same trend against POA temperature, which is instructive for SiC/SiO<jats:sub>2</jats:sub> interface quality improvement. Moreover, area dependence of TDDB characteristics for gate oxide on SiC shows different electrode areas lead to same slope of TDDB Weibull curves.</jats:p>

<jats:p>Organic/inorganic hybrid van der Waals heterostructure with an atomically abrupt interface has attracted great research interests within the field of multifunctional electronic and optoelectronic devices. The integration of organic rubrene films with inorganic Si semiconductors can avoid the atomic mutual-diffusion at the interface, and provide the possibility of forming two-dimensional van der Waals heterojunction accompanied with the type-II energy band alignment, due to the transfer behaviors of majority carriers at the interface. In this study, the high-quality rubrene/Si van der Waals heterostructure with an electronically abrupt junction was prepared, and a self-powered photodetector was then constructed based on this hybrid heterojunction. The photodetector demonstrated an excellent switching response to the 1064 nm monochromatic light with large on/off current ratio of 7.0 × 10<jats:sup>3</jats:sup>, the maximum photocurrent of 14.62 mA, the maximum responsivity of 2.07 A/W, the maximum detectivity of 2.9 × 10<jats:sup>11</jats:sup> Jones, and a fast response time of 13.0 μs. This study offers important guidance for preparing high-quality rubrene/Si hybrid van der Waals heterostructure with desirable band alignment, and the designed heterojunction photodetector has an important application prospect in the field of multifunctional optoelectronics.</jats:p>

<jats:p>The performance degradation of gate-recessed metal–oxide–semiconductor high electron mobility transistor (MOS-HEMT) is compared with that of conventional high electron mobility transistor (HEMT) under direct current (DC) stress, and the degradation mechanism is studied. Under the channel hot electron injection stress, the degradation of gate-recessed MOS-HEMT is more serious than that of conventional HEMT devices due to the combined effect of traps in the barrier layer, and that under the gate dielectric of the device. The threshold voltage of conventional HEMT shows a reduction under the gate electron injection stress, which is caused by the barrier layer traps trapping the injected electrons and releasing them into the channel. However, because of defects under gate dielectrics which can trap the electrons injected from gate and deplete part of the channel, the threshold voltage of gate-recessed MOS-HEMT first increases and then decreases as the conventional HEMT. The saturation phenomenon of threshold voltage degradation under high field stress verifies the existence of threshold voltage reduction effect caused by gate electron injection.</jats:p>

<jats:p>The on-surface synthesis from predesigned organic precursors can yield graphene nanoribbons (GNRs) with atomically precise widths, edge terminations and dopants, which facilitate the tunning of their electronic structures. Here, we report the synthesis of novel sulfur-doped cove-edged GNRs (S-CGNRs) on Au(111) from a specifically designed precursor containing thiophene rings. Scanning tunneling microscopy and non-contact atomic force microscopy measurements elucidate the formation of S-CGNRs through subsequent polymerization and cyclodehydrogenation, which further result in crosslinked branched structures. Scanning tunneling spectroscopy results reveal the conduction band minimum of the S-CGNR locates at 1.2 eV. First-principles calculations show that the S-CGNR possesses an energy bandgap of 1.17 eV, which is evidently smaller than that of an undoped cove-edged GNR (1.7 eV), suggesting effective tuning of the bandgap by introducing sulfur atoms. Further increasing the coverage of precursors close to a monolayer results in the formation of linear-shaped S-CGNRs. The fabrication of S-CGNRs provides one more candidate in the GNR toolbox and promotes the future applications of heteroatom-doped graphene nanostructures.</jats:p>

<jats:p>We theoretically study the transport properties in the T-shaped double-quantum-dot structure, by considering the dot in the main channel to be coupled to the Majorana bound state (MBS) at one end of the topological superconducting nanowire. It is found that the side-coupled dot governs the effect of the MBS on the transport behavior. When its level is consistent with the energy zero point, the MBS contributes little to the conductance spectrum. Otherwise, the linear conductance exhibits notable changes according to the inter-MBS coupling manners. In the absence of inter-MBS coupling, the linear conductance value keeps equal to <jats:italic>e</jats:italic> <jats:sup>2</jats:sup>/2<jats:italic>h</jats:italic> when the level of the side-coupled dot departs from the energy zero point. However, the linear conductance is always analogous to the MBS-absent case once the inter-MBS coupling comes into play. These findings provide new information about the leakage effect of MBSs in quantum-dot structures.</jats:p>

<jats:p>Pb(111) film is a special system that exhibits strong quantum size effects in many electronic properties. The collective excitations, <jats:italic>i.e.</jats:italic>, plasmons, in Pb(111) films are also expected to show signatures of the quantum size effect. Here, using high-resolution electron energy loss spectroscopy, we measured the plasmons on the surface of Pb(111) films with different film thicknesses and analyzed the plasmon dispersions. One surface plasmon branch exhibits prominent damping in the small momentum range, which can be attributed to the interaction between the top and bottom interfaces of the Pb(111) films. With the film thickness increasing, the critical momentum characterizing the damping in Pb(111) films decays not only much slower in Pb(111) films than in other metal films, and even in films with the thickness up to 40 monolayers the damping still exists. The slow decay of the surface plasmon damping, manifesting the strong quantum size effect in Pb(111) films, might be related to the strong nesting of the Fermi surface along the (111) direction.</jats:p>

<jats:p>We report the microwave synthesis and the doping effect of Mo<jats:sub>3−<jats:italic>x</jats:italic> </jats:sub>Re<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Al<jats:sub>2</jats:sub>C (0 ≤ x ≤ 0.3) superconductor. Re doping into Mo<jats:sub>3</jats:sub>Al<jats:sub>2</jats:sub>C results in a regular shrinkage of the lattice, marked by the linear decrease of lattice parameter <jats:italic>a</jats:italic> from 6.868(1) Å (for Mo<jats:sub>3</jats:sub>Al<jats:sub>2</jats:sub>C) to 6.846(2) Å (for Mo<jats:sub>2.7</jats:sub>Re<jats:sub>0.3</jats:sub>Al<jats:sub>2</jats:sub>C). Upon Re doping, <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> of Mo<jats:sub>3−<jats:italic>x</jats:italic> </jats:sub>Re<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Al<jats:sub>2</jats:sub>C first increases and then decreases, with the maximum <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> = 9.14 K at the optimal doping level of <jats:italic>x</jats:italic> = 0.09. Our report provides a convenient method to synthesize Mo<jats:sub>3−<jats:italic>x</jats:italic> </jats:sub>Re<jats:sub> <jats:italic>x</jats:italic> </jats:sub>Al<jats:sub>2</jats:sub>C within minutes, and also marks the first Re doping study with enhanced superconductivity on the non-centrosymmetric superconductor Mo<jats:sub>3</jats:sub>Al<jats:sub>2</jats:sub>C.</jats:p>

<jats:p>Superconducting transition edge sensor (TES) bolometers require superconducting films to have controllable transition temperatures <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> in different practical applications. The value of <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> strongly affects thermal conductivity and thermal noise performance of TES detectors. Al films doped with Mn (Al–Mn) of different concentrations can accomplish tunable <jats:italic>T</jats:italic> <jats:sub>c</jats:sub>. A magnetron sputtering machine is used to deposit the Al–Mn films in this study. Fabrication parameters including sputtering pressure and annealing process are studied and their influences on <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> and superconducting transition width Δ<jats:italic>T</jats:italic> <jats:sub>c</jats:sub> are optimized. The Al–Mn films with Δ<jats:italic>T</jats:italic> <jats:sub>c</jats:sub> below 1.0 mK for <jats:italic>T</jats:italic> <jats:sub>c</jats:sub> in a range of 520 mK–580 mK are successfully fabricated.</jats:p>

<jats:p>Discovery of a new superconductor with distinct crystal structure and chemistry often provides great opportunity for further expanding superconductor material base, and also leads to better understanding of superconductivity mechanisms. Here, we report the discovery of superconductivity in a new intermetallic oxide Hf<jats:sub>3</jats:sub>Pt<jats:sub>4</jats:sub>Ge<jats:sub>2</jats:sub>O synthesized through a solid-state reaction. The Hf<jats:sub>3</jats:sub>Pt<jats:sub>4</jats:sub>Ge<jats:sub>2</jats:sub>O crystallizes in a cubic structure (space group <jats:italic>Fm</jats:italic>-3<jats:italic>m</jats:italic>) with a lattice constant of <jats:italic>a</jats:italic> = 1.241 nm, whose stoichiometry and atomic structure are determined by electron microscopy and x-ray diffraction techniques. The superconductivity at 4.1 K and type-II superconducting nature are evidenced by the electrical resistivity, magnetic susceptibility, and specific heat measurements. The intermetallic oxide Hf<jats:sub>3</jats:sub>Pt<jats:sub>4</jats:sub>Ge<jats:sub>2</jats:sub>O system demonstrates an intriguing structural feature that foreign oxygen atoms can be accommodated in the interstitial sites of the ternary intermetallic framework. We also successfully synthesized a series of Hf<jats:sub>3</jats:sub>Pt<jats:sub>4</jats:sub>Ge<jats:sub>2</jats:sub>O<jats:sub>1 + <jats:italic>δ</jats:italic> </jats:sub> (–0.25 ≤ <jats:italic>δ</jats:italic> ≤ 0.5), and found the <jats:italic>δ</jats:italic>-dependent superconducting transition temperature <jats:italic>T</jats:italic> <jats:sub>c</jats:sub>. The atomic structure and the electronic structure are also substantiated by first-principles calculations. Our results present an entirely new family of superconductors with distinct structural and chemical characteristics, and could attract research interest in further finding new superconductors and exploring novel physics pertaining to the 5d-electron in these intermetallic compound systems.</jats:p>

<jats:p>Magnetic stiffness determines the stability of a high-temperature superconductor (HTS) magnetic levitation system. The quantitative properties of the physical and geometrical parameters that affect the stiffness of HTS levitation systems should be identified for improving the stiffness by some effective methods. The magnetic stiffness is directly related to the first-order derivative of the magnetic force with respect to the corresponding displacement, which indicates that the effects of the parameters on the stiffness should be different from the relationships between the forces and the same parameters. In this paper, we study the influences of some physical and geometrical parameters, including the strength of the external magnetic field (<jats:italic>B</jats:italic> <jats:sub>0</jats:sub>) produced by a rectangular permanent magnet (PM), critical current density (<jats:italic>J</jats:italic> <jats:sub>c</jats:sub>), the PM-to-HTS area ratio (<jats:italic>α</jats:italic>), and thickness ratio (<jats:italic>β</jats:italic>), on the lateral stiffness by using a numerical approach under zero-field cooling (ZFC) and field cooling (FC) conditions. In the first and second passes of the PM, the lateral stiffness at most of lateral positions essentially increases with <jats:italic>B</jats:italic> <jats:sub>0</jats:sub> increasing and decreases with <jats:italic>β</jats:italic> increasing in ZFC and FC. The largest lateral stiffness at every lateral position is almost produced by the minimum value of <jats:italic>J</jats:italic> <jats:sub>c</jats:sub>, which is obviously different from the lateral force–<jats:italic>J</jats:italic> <jats:sub>c</jats:sub> relation. The <jats:italic>α</jats:italic>-dependent lateral stiffness changes with some parameters, which include the cooling conditions of the bulk HTS, lateral displacement, and movement history of the PM. These findings can provide some suggestions for improving the lateral stiffness of the HTS levitation system.</jats:p>