Photo-Excited Carrier Dynamics in Ammonothermal Mn-Compensated GaN Semiconductor.

We investigated the carrier dynamics of ammonothermal Mn-compensated gallium nitride (GaN:Mn) semiconductors by using sub-bandgap and above-bandgap photo-excitation in a photoluminescence analysis and pump-probe measurements. The contactless probing methods elucidated their versatility for the complex analysis of defects in GaN:Mn crystals. The impurities of Mn were found to show photoconductivity and absorption bands starting at the 700 nm wavelength threshold and a broad peak located at 800 nm.

High-pressure band-gap engineering and structural properties of van der Waals BiOCl nanosheets.

van der Waals BiOCl semiconductors have gained significant attention due to their excellent photochemical catalysis, low-cost and non-toxicity. However, their intrinsic wide band gap limits visible light utilization. This study explores high-pressure band-gap engineering, a "chemical clean" method, to optimize BiOCl's electronic structure.

Interactions and ultrafast dynamics of exciton complexes in a monolayer semiconductor with electron gas.

We present femtosecond pump-probe measurements of neutral and charged exciton optical response in monolayer MoSe to resonant photoexcitation of a given exciton state in the presence of 2D electron gas. We show that creation of charged exciton (X) population in a given K, K valley requires the capture of available free carriers in the opposite valley and reduces the interaction of neutral exciton (X) with the electron Fermi sea. We also observe spectral broadening of the X transition line with the increasing X population caused by efficient scattering and excitation induced dephasing.

Possible Superconductivity Transition in Nitrogen-Doped Lutetium Hydride Observed at Megabar Pressure.

The pursuit of room-temperature superconductivity at an accessible synthetic pressure has been a long-held dream for both theoretical and experimental physicists. Recently, a controversial report by Dasenbrock-Gammon et al. claims that the nitrogen-doped lutetium trihydride exhibits room-temperature superconductivity at near-ambient pressure.

Controlled Formation of Silicon-Vacancy Centers in High-Pressure Nanodiamonds Produced from an "Adamantane + Detonation Nanodiamond" Mixture.

Despite progress in the high-pressure synthesis of nanodiamonds from hydrocarbons, the problem of controlled formation of fluorescent impurity centers in them still remains unresolved. In our work, we explore the potential of a new precursor composition, a mixture of adamantane with detonation nanodiamond, both in the synthesis of nanodiamonds and in the controlled formation of negatively charged silicon-vacancy centers in such nanodiamonds. Using different adamantane/detonation nanodiamond weight ratios, a series of samples was synthesized at a pressure of 7.

The Kob-Andersen model crystal structure: Genetic algorithms vs spontaneous crystallization.

The crystal structure of the Kob-Andersen mixture has been probed by genetic algorithm calculations. The stable structures of the system with different molar fractions of the components have been identified, and their stability at finite temperatures has been verified. It has been found that the structures of composition ABn, where n = 2, 3, or 4, can be formed in the system.

Orbital-selective effect of spin reorientation on the Dirac fermions in a non-charge-ordered kagome ferromagnet FeGe.

Kagome magnets provide a fascinating platform for the realization of correlated topological quantum phases under various magnetic ground states. However, the effect of the magnetic spin configurations on the characteristic electronic structure of the kagome-lattice layer remains elusive. Here, utilizing angle-resolved photoemission spectroscopy and density functional theory calculations, we report the spectroscopic evidence for the spin-reorientation effect of a kagome ferromagnet FeGe, which is composed solely of kagome planes.

Transfer learning for accurate description of atomic transport in Al-Cu melts.

Machine learning interatomic potentials (MLIPs) provide an optimal balance between accuracy and computational efficiency and allow studying problems that are hardly solvable by traditional methods. For metallic alloys, MLIPs are typically developed based on density functional theory with generalized gradient approximation (GGA) for the exchange-correlation functional. However, recent studies have shown that this standard protocol can be inaccurate for calculating the transport properties or phase diagrams of some metallic alloys.

Transparent (Ni,Au)/ZnO:Al-Based Ohmic Contacts to p-Type GaN as an Insight into the Role of Ni and Au in Standard p-Type GaN Contacts.

In this work, Ni/ZnO:Al and Au/ZnO:Al structures are proposed as efficient ohmic contacts to p-GaN. Through a careful selection of deposition parameters and annealing environment, we not only achieve the formation of high-quality ohmic contacts but also gain insights into the interfacial reactions, enhancing the understanding of conventional Ni/Au contact formation on p-GaN. In particular, the notion that the presence of NiO at the interface is enough for an ohmic contact to form is challenged by showing that in fact it has to be NiO formed at the interface from metallic Ni and additional oxygen.

Bandgap Characteristics of Boron-Containing Nitrides-Ab Initio Study for Optoelectronic Applications.

Hexagonal boron nitride (h-BN) is recognized as a 2D wide bandgap material with unique properties, such as effective photoluminescence and diverse lattice parameters. Nitride alloys containing h-BN have the potential to revolutionize the electronics and optoelectronics industries. The energy band structures of three boron-containing nitride alloys-BAlN, BGaN, and BInN-were calculated using standard density functional theory (DFT) with the hybrid Heyd-Scuseria-Ernzerhof (HSE) function to correct lattice parameters and energy gaps.

Food Preservation in the Industrial Revolution Epoch: Innovative High Pressure Processing (HPP, HPT) for the 21st-Century Sustainable Society.

The paper presents the 'progressive review' for high pressure preservation/processing (HPP) (cold pasteurization) of foods and the next-generation high-pressure and high temperature (HPHT, HPT) food sterilization technologies. It recalls the basics of HPP and HPT, showing their key features and advantages. It does not repeat detailed results regarding HPP and HPT implementations for specific foods, available in numerous excellent review papers.

Observation of Enhanced Long-Range Ferromagnetic Order in B-Site Ordered Double Perovskite Oxide CdCrSbO.

A B-site ordered double perovskite oxide CdCrSbO was synthesized under high-pressure and high-temperature conditions. The compound crystallizes to a monoclinic structure with a space group of 2/. The charge configuration is confirmed to be that of Cd/Cr/Sb.

Coulomb Contribution to Shockley-Read-Hall Recombination.

A nonradiative recombination channel is proposed, which does not vanish at low temperatures. Defect-mediated nonradiative recombination, known as Shockley-Read-Hall (SRH) recombination, is reformulated to accommodate Coulomb attraction between the charged deep defect and the approaching free carrier. It is demonstrated that this effect may cause a considerable increase in the carrier velocity approaching the recombination center.

Polarization-Doped InGaN LEDs and Laser Diodes for Broad Temperature Range Operation.

This work reports on the possibility of sustaining a stable operation of polarization-doped InGaN light emitters over a particularly broad temperature range. We obtained efficient emission from InGaN light-emitting diodes between 20 K and 295 K and from laser diodes between 77 K and 295 K under continuous wave operation. The main part of the p-type layers was fabricated from composition-graded AlGaN.

UV-assisted fluctuation-enhanced gas sensing by ink-printed MoS devices.

In this work, MoS flakes were printed on ceramic substrates and investigated toward 1-10 ppm of nitrogen dioxide (NO), 2-12 ppm of ammonia (NH), and 2-12 ppm acetone (CHO) under UV light (275 nm). The structure of overlapping MoS flakes and UV light assistance affected high responsivity to NO when DC resistance was monitored, and superior sensitivity to NH was obtained from the low-frequency noise spectra. MoS exhibited response and recovery times in hundreds of seconds and stability throughout the experiments conducted within a few months.

Absorption Spectra of AlGaN/GaN Terahertz Plasmonic Crystals-Experimental Validation of Analytical Approach.

Absorption spectra of AlGaN/GaN grating-gate plasmonic crystals with a period from 1 µm to 2.5 µm were studied experimentally at = 70 K using Fourier-transform infrared spectrometry. The plasmonic crystals exhibit distinct absorption lines of various plasmon harmonics across the 0.

AC Electric Conductivity of High Pressure and High Temperature Formed NaFePO Glassy Nanocomposite.

Olivine-like NaFePO glasses and nanocomposites are promising materials for cathodes in sodium batteries. Our previous studies focused on the preparation of NaFePO glass, transforming it into a nanocomposite using high-pressure-high-temperature treatment, and comparing both materials' structural, thermal, and DC electric conductivity. This work focuses on specific features of AC electric conductivity, containing messages on the dynamics of translational processes.

Using both faces of polar semiconductor wafers for functional devices.

Unlike non-polar semiconductors such as silicon, the broken inversion symmetry of the wide-bandgap semiconductor gallium nitride (GaN) leads to a large electronic polarization along a unique crystal axis. This makes the two surfaces of the semiconductor wafer perpendicular to the polar axis substantially different in their physical and chemical properties. In the past three decades, the cation (gallium) face of GaN has been used for photonic devices such as light-emitting diodes (LEDs) and lasers.

High-Temperature Superconductivity in Perovskite Hydride Below 10 GPa.

Hydrogen and hydride materials have long been considered promising materials for high-temperature superconductivity. However, the extreme pressures required for the metallization of hydrogen-based superconductors limit their applications. Here, a series of high-temperature perovskite hydrides is designed that can be stable within 10 GPa.

Effect of nanoparticles on the ex-vitro performance of cryopreservation-derived plant material.

The integration of nanoparticles into plant cryopreservation protocols holds great promise for improving the survival rates and recovery potential of explants. This study aimed to verify the effect of nanoparticles on the ex-vitro performance of cryopreservation-derived plants. Lamprocapnos spectabilis (L.