The energy landscapes and electronic properties of non-polar and polar nanofilms of silicon carbide are studied using periodic hybrid density functional calculations. Relative energies and electronic properties are reported as a function of film thickness for a set of structures derived from those of wurtzite, zinc blende and graphite. The energy landscape of the films is complex with pronounced nano-polymorphism. Across polar films different mechanisms in different cases remove or reduce the dipole moment, including charge transfer and phase transitions to the graphitic-like structures which are stable for the thinnest films. Graphitic structures are lowest in energy for the thinnest films. For ten layers non-polar films-zinc blende (110) and wurtzite(101-0) with tetrahedrally-coordinated Si and C in Si3C3rings in chair conformations-are lowest in energy, followed, ≈0.1 eV per formula unit higher in energy, by a body-centered tetragonal structure containing Si3C3rings in boat conformations. In the planar graphene structure the energy of the anti-site defect CSi-SiC(≈0.3 eV)) is more than an order of magnitude lower than in the bulk, suggesting a much higher degree of disorder in such films. One staggered graphitic-like structure with ABC stacking, a local minimum in the energy landscape, is of particular interest, since it lies in a regime of uncompensated polarity and possesses a direct band gap that decreases linearly with film thickness., from ≈2 eV (3 layers) to zero (6 layers).

The need to develop high-performance optoelectronic and semiconductor materials drives the search for new materials with tunable electronic and optical properties. The alkaline earth metal tellurides (AEMTe, where AEM = Be, Mg, Ca, Sr, and Ba) are particularly appealing among the group II-VI binary semiconductors because of their unique electrical structures and potential for band gap engineering. This study employs a thorough DFT-based methodology to examine the structural and optical characteristics of these structures. To guarantee high-fidelity findings, we combined scalar-relativistic ONCV pseudopotentials with RRKJ ultrasoft in the PBE-GGA framework. The core of our analysis centers on how the material shifts under strain; specifically, we evaluated electronic band structures at -5%, 0%, and +5% strains. This allowed us to determine exactly how compressive and tensile forces modify the compounds' fundamental characteristics. Phonon dispersion calculations confirm the dynamical stability of the cubic phases of BeTe, CaTe, SrTe, and BaTe, but suggest structural instability of the cubic Zinc Blende phase of MgTe. Notably, the band gap pressure coefficients are found to be anomalous, with most compounds showing negative pressure coefficients except for MgTe, which shows a strong positive pressure coefficient due to its dynamical unstable character. The exhaustive computational results demonstrate that the dynamical stable members of the AEMTe series offer very responsive and tunable electronic and dielectric environments. The strict qualitative trends offer strong evidence that epitaxial strain engineering might find successful applications to systematically tune absorption thresholds, dielectric screening and static refractive indices. Therefore, these strained alkaline earth metal tellurides are found to be very promising foundational candidates for future theoretical explorations and experimental integrations in advanced optoelectronics and strain-sensitive sensory architectures.

The self-catalyzed growth of InAs nanowires (NWs) on graphene is achievable but typically yields short, thick NWs with frequent stacking-fault defects. In this work, we demonstrate the successful synthesis of defect-free, ultralong InAs NWs by harnessing the synergistic effects of graphene and an Au catalyst. The distinct roles of graphene and Au in promoting the growth of high-quality NWs were systematically elucidated. Atomic resolution scanning transmission electron microscopy (STEM) imaging revealed that the Au-catalyzed InAs NWs grown on graphene predominantly exhibit defect-free wurtzite structures, whereas a small portion of nanosheets and the NWs grown atop them display defect-free zinc blende phases. Based on these observations, a growth model for Au-catalyzed InAs NWs on defective graphene/Ge surfaces was proposed.

Controlling the crystal phase and lattice mismatch of semiconductors offers a powerful route to engineer electronic and optical properties of heterostructures. As a consequence, semiconductors in the wurtzite phase are increasingly sought after, superseding the thermodynamically favored cubic zinc blende phase. Empirical atomistic modeling, required for large scale simulations of heterostructures and their properties, relies heavily on valence force field (VFF) methods to find the equilibrium atomic positions in an alloy. For zinc blende crystals, VFF models are well-established. In the case of wurtzite, VFF parameters are frequently adopted without rigorous analysis, despite subtle but critical differences from the zinc blende structure. Such an approach can compromise accuracy in describing material properties, since the structural differences between zinc blende and wurtzite directly influence electronic and optical characteristics. Based on the analytical VFF model by Tanneret al(2019Phys. Rev. B100094112), and using structural similarities between wurtzite and [111]-oriented zinc blende crystals, we guide the development of a wurtzite VFF without introducing additional parameters. Our framework utilizes analytic expressions and minimization routines to project zinc blende models onto wurtzite systems. Beyond elastic tensors, we train the model to reproduce bond length asymmetries and band gaps by using output of the VFF model in density functional theory (DFT) electronic structure calculations. Applied to wurtzite III-N compounds and BN, the model accurately reproduces targeted observables but also properties it has not been trained on, including the internal parameteru. We further validate the model on highly mismatched alloys such as (B,Ga)N and (B,In,Ga)N, exhibiting good agreement between VFF and DFT results when using identical supercells in these calculations.

Colloidal semiconductor nanocrystals (quantum dots) exhibit bright, narrowband, and spectrally tunable emission, making them attractive for photonic applications. Their emission properties are governed by closely spaced exciton fine structure, whose thermal mixing complicates control over key characteristics such as color purity, radiative rate, and polarization. Moreover, the lowest-energy excitonic state is typically non-emissive (dark), suppressing emission rates, particularly at cryogenic temperatures. Here we show that these limitations can be addressed by inducing controlled lattice distortion in zinc blende CdSe nanocrystals through pseudomorphic epitaxial growth of a ZnSe shell. This approach modifies the exciton fine structure by placing an emissive (bright) state at the lowest energy and increasing the separation between bright states derived from light- and heavy-hole subbands. These changes reduce thermal mixing, resulting in accelerated emission at low temperatures, sub-thermal linewidths, and polarization. These findings establish lattice distortion engineering as a strategy for controlling emission properties in colloidal nanocrystals.

We realized an exhaustive study about structural, electronic and optical properties of the quaternary alloys B1−xGaxPyBi1−y in zinc blend phase by applying the fullpotential augmented plane wave method FP-LAPW within the scope of density functional theory DFT. Potentials were determined using modified generalized gradient GGA and Becke-Johnson approximations. We analyzed the effects of the compositions (x, y) on the lattice parameters, bulk modulus, and band gap energy, revealing a non linear dependence of these quantities. We also investigated several optical constants, including the real and imaginary parts of the dielectric function, the absorption coefficient α(ω), the refractive index n(ω), and the reflectivity. Our obtained results about lattice parameters, energetic gaps and optical constants for the binary compounds are in well correspondence with the provided experimental and theoretical values. However, for alloys, differences were observed against linearity for lattice constants and bulk modulus. Moreover, we examined the energy band of zinc-based quaternary alloys B1−xGaxPyBi1−y those corresponding to ZnS lattice. It is worth mentioning that this study represents an innovative contribution in the domain of quaternary alloys, since it is the first theoretical analysis about these alloys.

Of late, indium phosphide (InP) nanowires (NWs) have garnered significant attention as foundational components for next-generation nanoelectronics, optoelectronics, and electromechanical devices, owing to their exceptional semiconducting and optical properties. Nevertheless, the practical integration of InP NWs remains hindered by the difficulty in precisely tailoring crystal orientation and mitigating intrinsic vacancy defects, both of which play a pivotal role in determining their mechanical performances. This work employs atomistic molecular dynamics simulations to systematically elucidate the influence of crystallographic orientation, size, temperature, and vacancy defects on the tensile mechanical behavior and deformation mechanisms of zincblende (ZB) and wurtzite (WZ) InP NWs. The results show significant anisotropy in mechanical response: ZB [111] NWs exhibit the highest elastic modulus (∼107 GPa) and fracture strength (∼8.3 GPa), whereas [100] NWs demonstrate superior ductility and fracture toughness. For WZ NWs, the [0001] orientation exhibits superior elastic modulus and strength compared to the [01−10] orientation. Elevated temperatures (100–600 K) anisotropically degrade the mechanical strength of ZB and WZ InP NWs, driven by orientation-dependent surface energy, interatomic spacing, and coordination. Vacancy defects—especially indium vacancies—significantly reduce the fracture stress (up to ∼31%) while the elastic modulus is found to be more sensitive to the removal of phosphorus atoms (up to ∼10% reduction) due to 1% vacancy. Orientation-dependent sensitivity to vacancy defects is evident: ZB [100] NWs exhibit the greatest reduction in elastic modulus, while [111] NWs are most susceptible to fracture strength degradation; conversely, WZ [01−10] NWs show pronounced stiffness loss, whereas [0001] NWs retain greater mechanical robustness. At low temperatures, failure in ZB InP NWs predominantly occurs along the {111} slip planes. However, at elevated temperatures, additional cleavage planes such as {100} become active due to increased bond instability and reduced interplanar spacing, leading to fracture at lower strain levels. This study provides an atomistic-level understanding of the interplay between crystal orientation, temperature, and defect conditions on the mechanical performance of InP NWs, offering critical design guidelines for high-performance and robust nanodevices. • Atomistic MD study reveals anisotropic tensile behavior in ZB and WZ InP nanowires. • ZB [111] and WZ [0001] show the highest strength; ZB [100] offers superior toughness. • Mechanical properties degrade anisotropically with increasing temperature. • Indium and phosphorus vacancies reduce fracture strength and modulus differently. • Temperature and defects alter slip activation and fracture mechanisms in InP NWs.

Simultaneous ferromagnetism and ferroelectricity in bulk zinc blende CrC with optical transparency at high-temperature

Co-doped CdSSe alloy quantum dots (QDs) were successfully synthesized via a wet chemical hot-injection method, with Co2+ doping concentrations ranging from 1 to 10% at. In addition to the intrinsic band gap tunability of CdSSe QDs, Co incorporation introduces magnetic functionality, enabling the development of diluted magnetic semiconductor nanostructures for optoelectronic and spintronic applications. The effects of sulfur/selenium ratio and cobalt doping on the structural, optical, photoluminescence, and magnetic properties of CdSSe QDs were systematically investigated. X-ray diffraction results confirm that both undoped and Co-doped CdSSe QDs crystallize in the cubic zinc blende structure, with no secondary phases detected. The lattice constant decreases with increasing Co concentration due to the substitution of smaller Co2+ ions for Cd2+ ions in the host lattice. Optical absorption and photoluminescence measurements reveal that the emission wavelength of CdS x Se1-x QDs can be effectively tuned across the visible region by adjusting the S/Se ratio. Upon Co2+ doping, a pronounced blue shift of both absorption and photoluminescence peaks is observed, accompanied by an increase in band gap energy, indicating strong modification of the electronic structure induced by Co-related energy levels. This behavior is attributed to the substitution of Cd2+ by smaller Co2+ ions, which induces compressive lattice strain and shifts the conduction band edge to higher energy. Time-resolved photoluminescence analysis shows a decrease in carrier lifetime with increasing Co concentration, attributed to enhanced non-radiative recombination via Co2+-induced trap states. Magnetic measurements demonstrate that Co-doped CdSSe QDs exhibit weak room-temperature ferromagnetism coexisting with diamagnetic behavior, with saturation magnetization increasing up to 5% Co doping and decreasing at higher concentrations due to the onset of antiferromagnetic interactions. These results demonstrate that Co doping is an effective method for simultaneously tuning the optical and magnetic properties of CdSSe QDs, making them promising candidates for optoelectronic and spintronic applications.

Mercury telluride (HgTe) nanocrystals are cornerstone materials for infrared optoelectronics, yet all previously reported forms of HgTe have crystallized in the zinc blende phase. Here, we develop a comprehensive cation exchange route to access metastable wurtzite (WZ) HgTe in both spherical and nanorod morphologies. Structural and spectroscopic characterizations show that WZ HgTe NCs retain the strong confinement tunability of their optical properties while introducing non-cubic lattice and distinct electronic topology. Ab initio modeling reveals that bulk WZ HgTe is a Dirac semimetal, whereas quantum confinement opens a direct gap that enables bright short-wave infrared emission. High-pressure studies demonstrate an irreversible WZ-to-zinc blende phase transition, consistent with its metastable nature, while the WZ phase remains stable at cryogenic temperatures. Electrically driven light-emitting diodes based on WZ HgTe nanorods exhibit superior electroluminescence beyond 2 μm, establishing a platform bridging topological semimetals and confined infrared emitters.

We realize strongly confined quantum dots (QDs) in InAs nanowires (NWs) by combining epitaxial crystal-phase control with chemical wet etching. A strong axial confinement is first introduced by growing closely spaced wurtzite (WZ) tunnel barriers in NWs to enclose a zinc blende (ZB) QD. The NW cross-section is then reduced by isotropic etching to obtain very small QDs, with a maximum observed charging energy>30 meV. Using low-temperature electrical characterization and finite-element method simulations, we study how charging energies and the onset of electron filling scale with QD diameter. For extremely small diameters, we identify a regime where stray capacitances become non-negligible, limiting further increase in charging energy by diameter reduction alone. This approach to increasing confinement is particularly relevant for understanding the strong spin-orbit interaction observed in crystal-phase QDs, possibly linked to polarization charges at the WZ/ZB interfaces. Small diameter QDs allow considerably weaker interfering electric fields when studied, but the QDs cannot be realized with epitaxial growth alone due to a loss of crystal phase control.

Zinc sulfide thin films were synthesized using the chemical bath deposition method with deposition durations ranging from 1 to 7 hours to examine the influence of deposition time and post-deposition annealing (60 °C to 100 °C) on their structural, optical, and electrical properties. X-ray diffraction confirmed the formation of the cubic zinc blende phase, with enhanced crystallinity and increased grain size at longer deposition times. Ultraviolet-visible spectroscopy revealed a tunable optical bandgap between ~3.5 and 3.8 eV, depending on deposition duration. Surface morphology and elemental composition were analyzed using scanning electron microscopy and energy-dispersive X-ray analysis. Energy-dispersive X-ray analysis results indicated that the 3-hour annealed film had a near-stoichiometric Zn:S ratio (41.1% Zn and 58.9% S), while the 1-hour annealed film exhibited a high oxygen content (70.31%) due to oxidation. Films annealed for 5 and 7 hours showed sulfur loss, resulting in zinc-rich compositions. Fourier-transform infrared spectroscopy confirmed improved Zn–S bonding over time, with sharper vibrational peaks in the 600–700 cm⁻¹ range and a marked reduction in organic and hydroxyl impurities. Among all samples, the 5-hour film showed the most favorable combination of crystallinity, purity, and low contamination, indicating its potential for optoelectronic applications. Electrical properties, evaluated using the two-probe method, demonstrated thermally activated conductivity in the 1-hour film annealed at 100°C, with an activation energy of 0.2857 eV, suggesting semiconducting behavior and applicability in thermoelectric and biosensing devices. However, electrical measurements for films deposited for 3, 5, and 7 hours were unfeasible due to extremely high resistivity and limited charge transport.

We systematically investigate the impact of ordered configurations of group III atoms on the formation enthalpy of zinc blende III–V alloys using first-principles calculations. The study focuses on 12 quasibinary systems: AlxGa1−xN, AlxIn1−xN, GaxIn1−xN, AlxGa1−xP, AlxIn1−xP, GaxIn1−xP, AlxGa1−xAs, AlxIn1−xAs, GaxIn1−xAs, AlxGa1−xSb, AlxIn1−xSb, and GaxIn1−xSb. Since the spatial distribution of group III cations in the zinc blende structure is equivalent to that in a face-centered cubic (FCC) lattice, FCC-based ordered phases are employed to compare formation enthalpies across different configurations. For compositions of x = 0.25 and 0.75, we compare the formation enthalpies of three ordered structures—L12, D023, and D022—with those of a random solid solution (RSS), in which group III elements are randomly distributed. At x = 0.5, four ordered structures—L10, L11, Y2, and chalcopyrite—are evaluated in comparison with the RSS structure. Our results reveal that for AlxGa1−xP, AlxGa1−xAs, and AlxGa1−xSb at x = 0.25 and 0.75, the RSS structure exhibits the lowest formation enthalpy, indicating a thermodynamic preference for disordered configurations. In contrast, at x = 0.5, the L11 structure is the most stable for these systems. For the remaining quasibinary systems, the D022 and chalcopyrite structures are energetically favored. However, all minimum formation enthalpies remain positive, suggesting that the ordered phases are thermodynamically metastable across the studied compositions. These findings offer fundamental insights into the relationship between atomistic ordering and formation enthalpy in III–V alloys, thereby providing a theoretical basis for predictive modeling and guiding future experimental efforts in materials design.

A classical interatomic potential for gallium antimonide (GaSb) was developed and thoroughly validated to reproduce its structural, mechanical, vibrational, and thermal properties. The model yields a lattice parameter, cohesive energy, bulk modulus, and elastic constants in close agreement with experimental measurements and density functional theory (DFT) results. The zinc-blende (ZB) phase is correctly stabilized, with a Ga-Sb bond length of 2.639 Å in excellent accordance with experiment. Defect energetics are well captured, with vacancy formation energies ofEVSb=3.17 eV andEVGa=0.84 eV, reproducing the established DFT trendEVSb>EVGa. Surface energies for the (001) and (110) facets fall within the expected analytical range. The potential also predicts the transition from the ZB structure to the Imma phase near 11 GPa, consistent with experimental observations. The computed vibrational density of states reproduces the main experimental features, including the positions of the acoustic and optical peaks. Thermal behavior is likewise well represented, with the specific heat matching the experimental temperature dependence, a room-temperature thermal conductivity of 30 W m-1 K-1, and a melting temperature of1050±50 K in good agreement with experiment.

The quaternary Cd 1− x − y Mn x Cr y Te semiconductor system ( x = 0.33 and 0.05 ≤ y ≤ 0.15) was synthesized by direct fusion of its constituent elements and characterized by X‐ray powder diffraction, with structural study using the Rietveld analysis. From the analysis, for the sample with y = 0.15, the diffraction pattern showed the presence of two phases with 97.22% wt of the principal phase Cd 0.52 Mn 0.33 Cr 0.15 Te and 2.78% wt of a secondary phase identified as the binary compound Cr 2 Te 3 . The Cd 1− x − y Mn x Cr y Te system crystallizes in the zinc blende structure, space group F3m (N° 216), with lattice parameters: a = 6.421(1) Å and V = 264.687(2) Å 3 for y = 0.15. As shown, the lattice constant of system decreases linearly with increasing Cr concentration, indicating that Cr ions partially substitute Cd sites in the CdTe host lattice, at least up to a concentration of 15%. The refinement of 26 instrumental and structural parameters converged with reliability factors of R p = 15.7%, R wp = 15.6%, R exp = 12.7%, and , based on 4000 intensity steps and 15 independent reflections for y = 0.15. Scanning electron microscopy was employed for a qualitative elemental analysis in selected regions of the samples. Comparison of the three samples revealed that the main difference is directly related to the Cr concentration. A progressive increase in Cr content induced variations in the microstructure and local atomic composition, with a more pronounced segregation observed in the samples with a higher Cr concentration.

First-Principles Investigation of Structural, Electronic, Elastic, Vibrational, and Thermodynamic Properties of HgSe in Zinc Blende (B3) and Cinnabar (B9) Phases

A hierarchical NiCo2O4@ZnS/MWCNT (NCO@Z-MWCNTs) nanocomposite was synthesized to serve as a platinum-free counter electrode for dye-sensitized solar cells (DSSCs). The nanocomposite comprised spinel NiCo2O4 nanorods, ZnS associated with the surface of the nanorods, and an interconnected multi-walled carbon nanotube (MWCNT) network, and it was synthesized via a low-temperature solution-based hydrothermal method. XRD confirmed the presence of cubic NiCo2O4 and zinc blende ZnS phases, while FESEM–EDS and XPS analyses verified the incorporation of ZnS and the formation of a conductive carbon framework interconnecting adjacent nanorods. ZnS, rather than acting as an isolated catalytic component, was considered to contribute additional sulfide-related surface sites and to modulate the interfacial electronic environment of the NiCo2O4 nanorods, which likely facilitated redox reactions involving the I−/I3− couple. Meanwhile, the MWCNT network established continuous electron transport pathways, effectively reducing interfacial resistance and enhancing charge-transfer efficiency. Thermogravimetric and electrochemical analyses revealed enhanced thermal stability, improved redox kinetics, and a significant reduction in charge-transfer resistance compared with pristine NiCo2O4.The optimized NCO@Z–MWCNT 9wt% counter electrode achieved a power conversion efficiency of 10.03% under AM 1.5 G illumination, exceeding that of the Pt reference device (9.6%). Overall, the improved performance was attributed to the combined contributions of ZnS surface modification and the conductive MWCNT network, which together enhanced charge transport and electrocatalytic activity. This work demonstrates a scalable strategy for developing cost-effective, durable, and high-performance counter electrodes for dye-sensitized solar cells.

ABSTRACT We calculate polarized Raman intensity of diamond and zinc‐blende crystal structure for arbitrary surfaces in a backscattering geometry using both linearly and circularly polarized light. Rotated Raman tensors are applied to the phonon mode of diamond and the (LO/TO) phonon modes of zinc blende to evaluate how the Raman intensity evolves as the surface orientation is varied from (100) toward (110) and (111). Polar plots versus sample rotation angle or analyzer angle show distinct behaviors for parallel (VV) and cross (VH) configurations under linear polarization, as well as helicity‐dependent configuration. Helicity‐dependent Raman spectroscopy reveals surface‐dependent tilts of the polar pattern. We derive the analytical expressions for the Raman intensities and for the angular positions of maxima and minima as explicit functions of . These surface orientation‐sensitive signatures enable identification of unknown , including sample miscut, and allow predictive modeling of polar‐plot evolution, improving the precision of polarized Raman surface metrology.

We extend our theoretical description of optical excitations in binary plasmonic supercrystals made of two types of metal nanoparticles to three common cubic structures: sodium chloride (NaCl), zinc blende (ZnS), and auricupride ( Cu 3 Au ). Our microscopic model of plasmon polaritons in supercrystals incorporates dipole and quadrupole nanoparticle excitations, their interactions, and their coupling with photons. We calculate the plasmon-polariton dispersion for the three cubic structures starting from the dipole and quadrupole energies obtained in the quasistatic approximation. The bands depend on the properties of the nanoparticles as well as the symmetry and the lattice parameters of the supercrystals. To gain further insight into the coupling of different excitations and develop a set of symmetry selection rules for each structure, we complement our calculations with an extensive group theory analysis. Comparing the results across various structures makes our symmetry analysis more general, enabling us to observe selection rules that apply to multiple structures.

Recently diamondoid semiconductors have attracted significant attention for thermoelectric applications due to their intrinsic low thermal conductivity and unique electrical transport properties. However, because of their compact tetrahedral coordination and strong chemical bonding, diamondoid materials are typically difficult to dope, resulting in low electrical conductivity, generally below 200Scm-1. In this work, we report an unusual metallic transport behavior in CdSe-doped pseudocubic diamondoid semiconductor Cu2ZnSnSe4. The intrinsic Cu2ZnSnSe4 possesses a zinc blende pseudocubic lattice. Owing to the structural compatibility of CdSe with Cu2ZnSnSe4, Cd is easily incorporated into the lattice. We find that substituting Sn4+ with Cd2+ increases the carrier concentration to ∼1021cm-3 without distorting the pseudocubic lattice. Due to the simultaneous improvement in carrier concentration and mobility, an unusually high room-temperature electrical conductivity of 1200Scm-1 is achieved in Cu2ZnSn0.9Cd0.1Se4, which exhibits metallic transport behavior. Furthermore, the thermal conductivity of the material is reduced through Ag alloying, which softens the chemical bonding and induces an off-centering effect. As a result, a peak ZT of 0.8 at 800K is achieved in Cu1.95Ag0.05ZnSn0.9Cd0.1Se4, highlighting the strong thermoelectric potential of this quaternary diamondoid system.