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A Fourier transform spectrometer (FTS) has been used to observe solar activities due to its ultra-high spectral resolution. However, the FTS in-band spectra are usually distorted and some artifacts appear in out-of-band regions due to nonlinear effects. Therefore, the FTS nonlinear problem must be corrected. In this study, we proposed a novel method to correct the nonlinear effects using simulated annealing. We simulated several nonlinear spectra to evaluate the performance of our method. The calculated quadratic coefficients are extremely close to the given values, demonstrating that the method is effective and accurate. The proposed method is further used to correct the blackbody and solar spectra with nonlinearity obtained by Bruker IFS-125HR installed at the Huairou Solar Observing Station, which is a pathfinder for the accurate infrared magnetic field measurements of the Sun project. To the blackbody spectra, the nonlinearity in low- and high-frequency regions are corrected by 89.09% and 60.84%. The nonlinear correction of the solar spectra in the low- and high-frequency regions have reached 65.34% and 81.04%, respectively. These results prove that our method can correct the nonlinear problem to improve the data accuracy.

Gate-grounded n-channel metal–oxide–semiconductor (GGNMOS) devices have been widely implemented as power clamps to protect semiconductor devices from electrostatic discharge stress owing to their simple construction, easy triggering, and low power dissipation. We present a novel I–V characterization of the GGNMOS used as the power clamp in complementary metal–oxide–semiconductor circuits as a result of switching the ESD paths under different impact energies. This special effect could cause an unexpected latch-up or pre-failure phenomenon in some applications with relatively large capacitances from power supply to power ground, and thus should be urgently analyzed and resolved. Transmission-line-pulse, human-body-modal, and light-emission tests were performed to explore the root cause.

We report the temperature effects on the performance of ferroelectric field-effect transistor (FeFET)-based non-volatile memory (NVM) considering random grain phase variation in the ferroelectric layer through simulation. Based on the FE temperature effect model that accounts for both the transistor and ferroelectric degradation, we demonstrate that: (1) at a certain temperature, the memory window (MW) decreases with pronounced effect on low threshold voltage shift and its variation increases as the FE phase decreases; (2) with the temperature increases, the MW decreases with pronounced effect on high threshold voltage shift. The random grain phase variation further exacerbates the MW distribution, thus degrading the sensing margin. These results may provide insights for device design of high-performance FeFET-based NVMs.

Bi4Br4 is a quasi-one-dimensional van der Waals topological insulator with novel electronic properties. Several efforts have been devoted to the understanding of its bulk form, yet it remains a challenge to explore the transport properties in low-dimensional structures due to the difficulty of device fabrication. Here we report for the first time a gate-tunable transport in exfoliated Bi4Br4 nanobelts. Notable two-frequency Shubnikov–de Haas oscillations oscillations are discovered at low temperatures, with the low- and high-frequency parts coming from the three-dimensional bulk state and the two-dimensional surface state, respectively. In addition, ambipolar field effect is realized with a longitudinal resistance peak and a sign reverse in the Hall coefficient. Our successful measurements of quantum oscillations and realization of gate-tunable transport lay a foundation for further investigation of novel topological properties and room-temperature quantum spin Hall states in Bi4Br4.

Ultrathin superconducting Nb films of about 8 nm thick have been deposited on heavily doped Si substrates through DC magnetron sputtering and then the high-quality Nb/Si superconductor–semiconductor heterojunctions have been fabricated by electron beam lithography and reactive ion etching. An abnormal magnetoresistance effect, which manifests itself as a zero field resistance peak under a magnetic field applied perpendicular to the interface, has been distinctly observed when the Nb film is in the superconductiing state. By considering the heterojunction interface being equivalent to the structure of superconductor–barrier layer–superconductor configuration, we could generally understand this unusual effect based on the Andreev reflection mechanism. Our results can be of help for the future development on compatibility and scalability of the silicon-based nanoscale superconducting devices for integrated circuits and superconducting quantum electronics.

In this study, the impact of interfacial charges including fixed charges and acceptor-type traps between the dielectric and the channel in negative capacitance ferroelectric FETs (FeFETs) is investigated by simulation based on the Landau–Khalatnikov model. The results reveal the separate impact of the fixed charges and acceptor-type traps on device performance degradation, respectively, including the subthreshold swing (SS), switching current (I on and I off) and threshold voltage (V T). On this basis, the combined impact of interfacial charges with the fixed charges and acceptor-type traps co-existing equally is further explored. Our findings indicate that the fixed charges play a key role in the V T and I off, while the acceptor-type traps predominate in the SS and I on. This study helps to understand the degradation mechanism of FeFETs and extend the device end-of-lifetime.

A transfer reaction and cluster-decay experiment, C( O, Mg α+ Ne)α, was performed at a beam energy of 96 MeV. Both recoil and decay α particles were detected in coincidence, allowing us to deduce the energy-momentum of a Ne fragment. A number of resonant states of Mg were reconstructed up to an excitation energy of approximately 30 MeV. Owing to the experimentally achieved excellent resolutions of the Q-value and excitation-energy spectra, the relative decay widths for each resonant state in Mg to various final states of Ne were extracted, along with the total decay width. The obtained results provide good testing ground for theoretical descriptions of multiple clustering configurations in Mg.

We study the lattice QCD Λ c N phase shifts for the 3 S 1–3 D 1 coupled channel using both the leading order covariant chiral effective theory and the next-to-leading order non-relativistic chiral effective field theory (ChEFT). We show that although it is possible to describe simultaneously the 3 S 1 and 3 D 1 phase shifts and the inelasticity η 1, the fitted energy range is quite small, only up to E c.m. = 5 MeV. This raises concerns regarding the consistency between leading/next-to-leading order ChEFT and the lattice QCD simulations.

Dynamic states in mutual-coupled mid-infrared quantum cascade lasers (QCLs) were numerically investigated in the parameter space of injection strength and detuning frequency based on the Lang–Kobayashi equations model. Three types of period-one states were found, with different periods of injection time delay τ inj, 2τ inj, and reciprocal of the detuning frequency. Besides, square-wave, quasi-period, pulse-burst and chaotic oscillations were also observed. It is concluded that external-cavity periodic dynamics and optical modes beating are the mainly periodic dynamics. The interaction of the two periodic dynamics and the high-frequency dynamics stimulated by strong injection induces the dynamic states evolution. This work helps to understand the dynamic behaviors in QCLs and shows a new way to mid-infrared wide-band chaotic laser.

Bionic robot fish have been widely used in various underwater exploration activities due to their advantages of low noise, low resistance, high flexibility and high concealment. A dielectric elastomer (DE) is a soft material that significantly deforms under the action of an electric field. It has the characteristics of large strain, flexibility, high energy density and fast response speed, which lead to its unique advantages in the actuation of bionic fish. In this paper, the actuation characteristics of a dielectric elastomer are used to design and prepare a limit-type antagonistic dielectric elastomer actuator (DEA). A BCF bionic robot fish is proposed based on the DEA, which has a maximum swimming speed of 22.7 mm/s.

Quantum cascade lasers (QCLs) suffer from catastrophic failure caused by serious self-heating, thus limiting their output power and working stability. In this study, we observed a distinctive failure morphology on the back facet of watt-level power QCL emitting at λ ∼ 7.7 µm. The failure was caused by a massive localized current and the channel of the massive current can be observed in the cavity. Because the massive current significantly increased temperature nearby, two burned holes were formed around the channel. A 3D thermal model shows that the back facet is a vulnerable location for failure because light absorption by the high-reflectance metal coating increases the facet temperature significantly. However, the starting point of the massive current has a certain distance from the facet which is the hottest location in the cavity. Therefore, we conduct a hypothesis that the cause of the massive current is thermal strain relaxations induced by temperature gradient. We calculated the positions of the relaxation points and one of them correspond with the failure starting point found experimentally. The strain relaxation damaged the active region, thus leading to the formation of the massive current.

It is known that ion-focused regime (IFR) can effectively suppress expansion of a relativistic electron beam (REB). Using the particle-in-cell Monte Carlo collision (PIC-MCC) method, we numerically investigate the propagation of an REB in neutral gas. The results demonstrate that the beam body is charge neutralization and a stable IFR can be established. As a result, the beam transverse dimensions and longitudinal velocities keep close to the initial parameters. We also calculate the charge and current neutralization factors of the REB. Combined with envelope equations, we obtain the variations of beam envelopes, which agree well with the PIC simulations. However, both the energy loss and instabilities of the REB may lead to a low transport efficiency during long-range propagation. It is proved that decreasing the initial pulse length of the REB can avoid the influence of electron avalanche. Using parts of REB pulses to build a long-distance IFR in advance can improve the beam quality of subsequent pulses. Further, a long-distance IFR may contribute to the implementation of long-range propagation of the REB in space environment.

Trifluoromethane is an important etching gas in semiconductor industries as the fluorine source in reactive etching plasma. Electron impact excitations into the dissociation states are essential for plasma modeling. By employing an angle-resolved electron energy loss spectrometer, the generalized oscillator strengths (GOSs) for the valence-shell excited states have been determined at an absolute scale utilizing the crossed-beam based relative flow technique. The measurement was performed with an incident electron energy of 1500 eV at an energy resolution of about 70 meV. The corresponding optical oscillator strengths are also obtained by extrapolating the measured GOSs to the limit of zero momentum transfer. The extrapolated data and fitted linewidths are used to reproduce the photoabsorption spectra and compare with the available experimental and theoretical results. In addition, the integral cross sections from the excitation threshold to 5000 eV of the associated excited states have been derived by using the BE-scaling method. The resulted data can not only be used in plasma models but also serve as a benchmark for further theoretical calculations.