Quantum well systems based on semiconductors with the wurtzite crystalline structure have found widespread applications in photonics and optoelectronic devices, such as light-emitting diodes, laser diodes, or single-photon emitters. In these structures, the radiative recombination processes can be affected by (i) the presence of strain and polarization-induced electric fields, (ii) quantum well thickness

Perspectives about growth of bulk gallium nitride crystals, fabricating high structural quality gallium nitride wafers and the market demand for them are presented. Three basic crystal growth technologies, halide vapor phase epitaxy, sodium flux, and ammonothermal, are described. Their advantages and disadvantages, recent development, and possibilities are discussed. The main difficulty with crystallization

All-inorganic perovskite CsPbX3 nanocrystals (NCs) have made remarkable achievements in optoelectronic applications due to their enhanced stability, low-cost, easy-to-perform synthetic routes, broad emission spectra tunability, and high photoluminescence quantum yields, especially for light emitting diodes (LEDs) and solar cells (SCs). In this perspective, the structure and optoelectronic properties

This Tutorial provides an overview of the techniques that are most commonly utilized to grow bulk van der Waals crystals. The materials discussed were selected to highlight various challenges that are often encountered during crystal growth. In relatively equal parts, the text covers melt-based techniques, vapor transport growths, and the characterization of crystal quality with an emphasis on structural

We demonstrate the possibility of using a two-dimensional array of spheroidal metallic nanoparticles embedded in a one-dimensional photonic crystal to obtain a narrow-bandpass, polarization-sensitive dichroic filter operating in the near-UV and visible domains. The optical anisotropy of the array of identically oriented nanoparticles results in two spectrally distinct plasmon resonances independently

CdSeTe alloying has significantly increased the efficiency of CdTe-based solar technology. Here, computational modeling compares how different CdSeTe bandgrading, carrier lifetimes, band alignment, and carrier concentrations contribute to transport, recombination, and performance. We find that the gain in photocurrent caused by bandgap narrowing alone is insufficient to describe experimental efficiency

While solid and hollow microsphere composites have received significant attention as solar reflectors or selective emitters, the driving mechanisms for their optical properties remain relatively unclear. Here, we study the solar reflectivity in the 0.4–2.4 μm wavelength range of solid and hollow microspheres with the diameter varying from 0.125 μm to 8 μm. SiO2 and TiO2 are considered as low- and

We consider the possibility of difference frequency generation in the GaAs phonon reststrahlen band within dual-chip GaAs-based lasers at room temperature. Sufficient generation efficiency is achieved via the resonant increase of GaAs second order nonlinear susceptibility in this spectral range. The outcoupling power conversion efficiency is anticipated to be up to 4 × 10−7 W−1 in the laser design

The ion accumulation within the negatively charged dust cloud embedded in a plasma of dc glow discharge has been studied numerically under the conditions corresponding to recent experiments. The characteristics of neon plasma in a positive column of dc discharge with various densities of micron-sized particles have been simulated by a diffusion-drift model with the use of experimental values of parameters

A theoretical investigation of electronic and magnetic properties has been performed on the new members of Heusler alloys M2NiZ (M = Sc, Ti, and V; Z = Tl and Pb) that crystallize in an inverse Heusler XA structure. The overall electronic properties and magnetic moments are predominated by M atoms, where the total magnetic moment varies linearly with the number of valence electrons, following the Slater–Pauling

Spin–orbit torque that originates from spin Hall effect and Dzyaloshinskii–Moriya interaction (DMI) can efficiently move chiral magnetic domain walls in perpendicularly magnetized wires. It has been shown that antiferromagnetically coupled composite domain walls across a ruthenium layer can be driven even faster by exchange coupling torque that is proportional to exchange coupling strength. Here, we

In the theory of dilute magnetic impurities in superconductors, the effect of all impurity spin-components is expressed via a single magnetic scattering rate Γ m. In a more realistic setting, magnetic impurities are anisotropic. In this case, the spatial randomness of three spin-components of impurities gives rise to generally different scattering rates Γ i ( i = 1 , 2 , 3). We explore the effects

We report the electrical detection of the antiferromagnetic state of IrMn through anomalous Hall measurements in Ta/IrMn heterostructures. The magnetic state is set in the antiferromagnet through field cooling and detected electrically by transverse resistance measurements in Hall bar structures without the need for any ferromagnetic layer. The amplitude of the signal increases with the magnetic field

Magnetic stiffness is as important as vertical and lateral forces to achieve stable levitation in high-temperature superconductor (HTS) levitation systems. To date, research on magnetic stiffness has mainly focused on a few aspects, but the understanding of its comprehensive characteristics has not been included. This study is focused on the quantitative properties of the physical and geometrical parameters

Hafnium–zirconium oxide (HZO) thin films are of interest due to their ability to form ferroelectric (FE) and antiferroelectric (AFE) oxide phases. Density functional theory is employed to elucidate the stabilization mechanisms of both FE HZO thin films and AFE ZrO2 films. The FE orthorhombic phase is primarily stabilized by in-plane tensile strain, which spontaneously occurs during the synthesis process

Ca3Ti2O7 with a Ruddlesden–Popper structure has received great scientific attention due to its high ferroelectric polarization. However, the optimization of hybrid improper ferroelectricity is still a challenging issue. In the present work, the remarkably improved ferroelectric polarization has been achieved in B-site co-substituted Ca3Ti1.8Al0.1Nb0.1O7 ceramic. The improved ferroelectric polarization

The molecular dynamics method based on the shell model is used to investigate the polarization configuration evolution in compressed BaTiO3 nanofilms with oxygen vacancy lattices of different volume fractions and positions. A clockwise closure domain surrounding a head-to-head domain is observed for a single oxygen vacancy nanofilm. With an increasing oxygen vacancy fraction, the closure domain around

The morphotropic phase boundary (MPB) plays an important role in ferroelectric materials. Typically, two phases coexist in materials near the MPB. Such materials usually exhibit large piezoelectricities, dielectricities, and actuation strains. In this work, we produce an MPB-like effect in hybrid electrically poled, mechanically depolarized (HEPMD) BaTiO3 and lead zirconate titanate ceramics where

The universal tendency in scanning probe microscopy (SPM) over the last two decades is to transition from simple 2D imaging to complex detection and spectroscopic imaging modes. The emergence of complex SPM engines brings forth the challenge of reliable data interpretation, i.e., conversion from detected signals to descriptors specific to tip–surface interactions and subsequently to material’s properties

Nanodiamonds (NDs) hosting nitrogen-vacancy (NV) centers are promising for applications of quantum sensing. Long spin relaxation times ( T 1 and T 2) are critical for high sensitivity in quantum applications. It has been shown that fluctuations of magnetic fields due to surface spins strongly influence T 1 and T 2 in NDs. However, their relaxation mechanisms have yet to be fully understood. In this

Si/Ge nanostructures have attracted much attention since they are compatible with current microelectronics technology. The geometry and composition variations can be used to tune their electronic properties. Here, we introduce a 3D Si/Ge superlattice, metalattice, made of more volumetric meta-atoms and thinner metabonds between them. Its size varies from a few tens to hundreds of nanometers and can

Porous nanoparticles are very popular because of their high surface/volume ratio; moreover, they have stronger plasmonic properties than their solid counterparts. Due to these properties, these are potential candidates in optical, or even in ophthalmological applications. We prepared porous gold nanoparticles on SiO 2 / Si as well as on sapphire substrates with solid-state dewetting–dealloying methods

Vertically aligned ZnO nanorods grown by a wet chemical method were implanted with O + ions with three different ion fluences: ( Φ ) = 5 × 10 14, 5 × 10 15, and 5 × 10 16 ions/cm 2. It is observed that the concentration of Oxygen vacancies (O V) introduced by implantation first increases from 25.94 % to 54.76 % with increasing Φ and decreases beyond Φ = 5 × 10 15 ions/cm 2. We attribute this to the

One hundred and forty years after his discovery, the Hall effect still deserves attention. If it is well-known that the Hall voltage measured in Hall bar devices is due to the electric charges accumulated at the edges in response to the magnetic field, the nature of the corresponding boundary conditions is still problematic. In order to study this out-of-equilibrium stationary state, the Onsager’s

Machine learning is quickly becoming an important tool in modern materials design. Where many of its successes are rooted in huge datasets, the most common applications in academic and industrial materials design deal with datasets of at best a few tens of data points. Harnessing the power of machine learning in this context is, therefore, of considerable importance. In this work, we investigate the

This article numerically investigates the effects of different control strategies on combustion instability (also known as thermoacoustic instability) based on a lean-premixed combustor. Combustion instability occurs in the combustor with a sound pressure level of 51 Pa and an oscillation frequency of 271 Hz. Experimental results and the geometric data of the unstable combustor were modeled for thermoacoustic

An atmospheric pressure plasma (APP) system offers advanced, cost-effective processing routes for surface cleaning without a vacuum chamber. The appeal of APP systems in surface cleaning, however, is reduced by lack of a predictive link among the processing parameters, surface-plasma reactions, and plasma chemistry responsible for efficient removal. Here, we present a comprehensive multiphysics model

Imaging mechanisms in contact Kelvin probe force microscopy (cKPFM) are explored via information theory-based methods. Gaussian processes are used to achieve super-resolution in the cKPFM signal, effectively extrapolating across the spatial and parameter space. Tensor factorization is applied to reduce the multidimensional signal to the tensor convolution of the scalar functions that show a clear trending

A series of the formation energies Ef of boron dopants in Si quantum dots with different shapes, including tetrahedron (TH), tetrahedron-centered (TC), and octahedron (OT), are investigated by the first-principle calculation. The site of B dopants can be simply divided into vertex (“′v”), edge (“e”), and facet (“f”) on the surfaces of the Si quantum dots. It is found that the Ef value is strongly relying

The internal friction of Cu50Zr50 metallic glass nano-pillars was investigated by using molecular dynamics simulations. An unusual non-monotonic variation of internal friction is revealed against the size of the specimen, which differs significantly from that of the bulk metallic glass. Meanwhile, by analyzing the rearranged atoms with high mobility, which play a vital role in affecting the internal

This work is a systematic investigation of electronic transport and inelastic effects of two-terminal devices without gates composed of zigzag and armchair phagraphene nanoribbons doped with boron nitride. It is based on a hybrid density functional theory and the nonequilibrium Green’s function method implemented in the TRANSIESTA code. The doping in the device with a zigzag conformation had a metal–semiconductor

High-temperature superconductors such as REBa2Cu3O7 − δ (REBCO, RE = rare earth) enable high-current cables and high-field magnets. By removing the turn-to-turn insulation in a magnet application, recent experiments demonstrated that REBCO magnets can self-protect against catastrophic damage during a superconducting-to-normal transition (quench), i.e., when the stored magnetic energy rapidly converts

We report 59 Co, 93 Nb, and 121 Sb nuclear magnetic resonance measurements combined with density functional theory (DFT) calculations on a series of half-Heusler semiconductors, including NbCoSn, ZrCoSb, TaFeSb, and NbFeSb, to better understand their electronic properties and general composition-dependent trends. These materials are of interest as potentially high efficiency thermoelectric materials

The time-domain thermoreflectance (TDTR) technique has been widely used to measure thermal properties. The design and interpretation of the TDTR experiment rely on an in-depth understanding of the thermoreflectance signature for a given metal thermal transducer. Although the TDTR signals of several metal thermal transducers have been experimentally investigated, a practical framework bridging the electronic

The structural and dielectric properties of gadolinium oxide (Gd 2O 3) grown on Si(001) depending on the epitaxial growth conditions were investigated. Gd 2O 3 layers were grown at temperatures between 250 ° C and 400 ° C with an oxygen partial pressure between 2 × 10 − 7 mbar and 5 × 10 − 7 mbar. The crystal structure of the Gd 2O 3 turns out to be monoclinic with rotational domains as revealed by

A magnetostrictive ferromagnet–polymer composite consisting of steel wires suspended in a polymer matrix has been developed that exhibits large reversible magnetostrictive strain in relatively low magnetic fields. The strain for a fixed field is a nonmonotonic function of wire loading for the longer wires investigated, and the strain for a given wire loading increases with decreasing the wire length

Ribbon-shaped magnetocaloric materials are favorable to achieve high heat-transfer efficiencies due to their large specific surface area. In this work, Mn50Ni41−xIn9Cox (0 ≤ x ≤ 4) ribbons were prepared using a melt-spinning technique, and the corresponding phase transformation and magnetocaloric properties were studied. The large temperature gradient during melt-spinning caused the initial austenite

The damage evolution and spall behavior of copper under complex shockwave loading conditions were investigated using plate impact experiments with conical targets. Sweeping tensile waves were generated by the interaction of the released waves that were reflected from the free surfaces of the impactor and the cone surface. From the free-surface velocity profiles measured by multi-channel velocimetry

Using genetic algorithms for an unbiased structure search and first-principles total-energy calculations, a stable manganese nitride, Mn3N, is discovered. Mn3N is a nonmagnetic metal and isostructural to superhard Re3N. Mn3N exhibits a large bulk modulus and incompressibility comparable to that of the ultra-incompressible OsB. We show that the large bulk modulus can be attributed to the strong covalent

The effect of low-angle off-axis GaN substrate orientation on the surface morphology of Mg-doped GaN epilayers has been studied using atomic force microscopy (AFM) and transmission electron microscopy. Undoped- and magnesium-doped GaN layers were grown on (0001) GaN surfaces tilted by 0.3°, 2°, and 4° toward a ⟨ 1 1 ¯ 00 ⟩ direction. AFM images show the presence of pinholes associated with threading

Pure perovskite phase, (001)-oriented, epitaxial thin films of (Pb(Mg1/3Nb2/3)O3)0.67-(PbTiO3)0.33 (PMN-PT) were fabricated on single crystal, (001)-oriented SrTiO3 substrates using a hard (Fe-doped) and soft doped (Nb-doped) PZT(52/48) interfacial layer. The effect of different interface layers on the structural and ferroelectric properties of the PMN-PT films was investigated in detail. A significant

The ground-breaking properties of biaxially textured thin films have attracted increasing attention to the characterization and growth theory of their crystal morphologies. In particular, multi-faceted columnar structures developed during oblique angle deposition (OAD) show abnormal tilt angles that have not been previously captured by existing models. Current theories for the formation of biaxially

Rare earth ions hosted in solids are good candidates for quantum technologies due to their chemical stability and optical and spin transitions exhibiting long coherence lifetimes. While bulk oxide crystals are usually the preferred host material, the development of a scalable silicon-compatible thin film platform would be desirable. In this paper, we report on the growth of Y2(1−x)Eu2xO3 thin films

A novel resonator-based metasurface is devised to control reflected underwater waves. Each metasurface unit is constructed with an aluminum plate attached to a lead mass. By tailoring the thickness of the plate, full 2π phase shift of the reflected wave can be achieved. Examples of redirection, focusing, and directional carpet cloaking are demonstrated as applications. The target frequency can be as

Incorporating two-dimensional transition metal dichalcogenides (TMDs) into electronic and optoelectronic applications requires a fundamental understanding of metal/TMD interactions. This work applies a fast and easy approach to observe reactivity between metal contacts and monolayer (1L) WS2 via Raman spectroscopy using both destructive and non-destructive methods. We compare findings from Raman spectra

The equilibrium shape of nanoparticles is investigated to elucidate the various core–shell morphologies observed in a bimetallic system associating two immiscible metals, iron and gold, that crystallize in the bcc and fcc lattices, respectively. Fe–Au core–shell nanoparticles present a crystalline Fe core embedded in a polycrystalline Au shell, with core and shell morphologies both depending on the

This work investigates the optical and interfacial properties of epitaxially fused direct GaInP/Si heterojunctions realized by the corrugated epitaxial lateral overgrowth (CELOG) approach. To provide a broad analysis of the above heterojunction, photoluminescence (PL), cathodoluminescence (CL), Raman, and high-resolution transmission electron microscopy (TEM) were employed in this study. The enhanced

The presence of redox reactions due to slow-moving ions at perovskite/contact interfaces is a major concern for the long-term stability of perovskite solar cells. In this work, we have evidently demonstrated the contribution of K+ ions on the removal of these non-capacitive effects that primarily accelerate the degradation mechanism in the devices. The intermittent current–voltage characteristics at

Photoluminescence (PL) measurements at a wide temperature range, up to room temperature, for high-quality and high-density GaAs/AlGaAs quantum dots (QDs) fabricated by droplet epitaxy were carried out to investigate the anomalous temperature dependence of the PL peak energy from the QD ensemble. In addition to a reported redshift that deviated from the so-called Varshni's curve of the PL peak energy

The almost periodic streaming motion of accelerated electrons under moderate electric fields coupled with almost periodic emission of longitudinal optical (LO) phonons is studied in a gallium nitride quantum-well—a promising pathway for terahertz (THz) oscillations. The optimal conditions for the LO-phonon-terminated streaming depend, among others, on the density of the electron gas, the low-field

Due to the advent of antiferromagnetic (AF) spintronics, there is a burgeoning interest in AF materials for a wide range of potential and actual applications. Generally, AFs are characterized via the ordering at the Néel temperature (TN), but to have a stable AF configuration, it is necessary that the material has a sufficient level of anisotropy so as to maintain the orientation of the given magnetic

Following astonishing growth in the last decade, the field of luminescence thermometry has reached the stage of becoming a mature technology. To achieve that goal, further developments should resolve inherent problems and methodological faults to facilitate its widespread use. This perspective presents recent findings in luminescence thermometry, with the aim of providing a guide for the reader to

Pressure-induced phase transitions in orthovanadates have led to interesting physical phenomena. The observed transitions usually involve large volume collapses and drastic changes in the electronic and vibrational properties of the materials. In some cases, the phase transitions implicate coordination changes in vanadium, which has important consequences in the physical properties of vanadates. In

Antiferromagnetic materials have recently gained renewed interest due to their possible use in spintronics technologies, where spin transport is the foundation of their functionalities. In that respect, metallic antiferromagnets are of particular interest since they enable complex interplays between electronic charge transport, spin, optical, and magnetization dynamics. Here, we review the phenomena

Surface plasmons have shown increasingly widespread applications in the last decade, especially in the field of solar energy conversion, recently leading to the use of metal nanoparticles as plasmonic photocatalysts. The latter offers great potential in overcoming traditional catalysts by providing localized heating and unconventional reaction pathways leading to improved product selectivity. A complete

Statistical fluctuations in the alloy composition on the atomic scale can have important effects on electronic and optical properties of bulk materials and devices. In particular, carrier localization induced by alloy disorder has been a much discussed topic during the last decade with regard to III-nitride light emitting diodes (LEDs). Much experimental and theoretical work has been dedicated to the

This tutorial introduces systematically the foundational concepts undergirding the recently formulated AI (artificial intelligence)-based materials knowledge system (AI-MKS) framework. More specifically, these concepts deal with features engineering the heterogeneous material internal structure to obtain low-dimensional representations that can then be combined with machine learning models to establish

The substrate effect is an important issue in the properties of two-dimensional transition metal dichalcogenides (2D TMDs). Quantitatively determining the dependence of the photoluminescence (PL) emission properties and the excitonic behavior of single-layer 2D materials in a specific dielectric environment would provide helpful guidance for the rational design of substrates for high performance 2D

Methylammonium (MA)-free perovskite solar cells (PVSCs) have obtained great attention recently, owing to their superior stability. However, there are still gaps in efficiency between MA-free PVSCs and MA-containing counterparts. Their stability still needs to be further enhanced for meeting commercial standards, especially the illumination stability. Here, we incorporate Zn2+ into perovskite thin films

Constructing van der Waals (vdW) heterojunctions via stacking different two-dimensional materials is an effective approach to obtain desirable properties. By using the first-principles calculation, we explore the vdW heterojunction based on the Janus structure of the 1T-PtTe2 for the potential application in the excitonic solar cell. The SePtTe/InS vdW heterojunction is found to be an appropriate material