Injecting spin-polarized carriers into semiconductor lasers provides important opportunities to extend what is known about spintronic devices, as well overcome many limitations of conventional (spin-unpolarized) lasers. By developing a microscopic model spin-dependent optical gain derived from an accurate electronic structure in quantum-well-based laser, we study how its operation properties can be modified by carriers, carrier density, and resonant cavity design. We reveal that applying...

In this work, we report an ab initio investigation based on density functional theory of the structural, energetic and electronic properties 2D layered chalcogenides compounds in combination transition-metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W (S, Se, Te) three polymorphic phases: trigonal prismatic (2H), octahedral (1T) distorted (1T$_{\text{d}}$). We determined most stable phases for each compound, verifying existence 1T$_{\text{d}}$ phase a small number have also identified magnetic...

Semiconductor nanowires based on non-nitride III-V compounds can be synthesized under certain growth conditions to favor the appearance of wurtzite crystal phase. Despite reports in literature ab initio band structures for these compounds, we still lack effective multiband models and parameter sets that simply used investigate physical properties such systems, instance, quantum confinement effects. In order address this deficiency, study calculate structure bulk InAs InP phase develop an...

Ferromagnet/graphene (F/Gr) junctions are important building blocks for graphene spintronics. While simple models of spin injection very successful macroscopic metallic junctions, they reveal many deficiencies in describing F/Gr junctions. First-principles methods key to assess such Gr-based but the computational cost is often too high. We focus on Ni(111)/Gr and include van der Waals interactions from first principles, crucial their correct description. formulate a computationally...

Magnetic linear dichroism and birefringence in (Ga,Mn)As epitaxial layers is investigated by measuring the polarization plane rotation of reflected linearly polarized light when magnetization lies sample. We report on spectral dependence ellipticity angles a broad energy range $0.12--2.7\phantom{\rule{4pt}{0ex}}\mathrm{eV}$ for series optimized samples covering wide Mn dopings Curie temperatures find clear blueshift dominant peak at exceeding host material band gap. These results are...

Semiconductor nanowhiskers (NWs) made of III-V compounds exhibit great potential for technological applications. Controlling the growth conditions, such as temperature and diameter, it is possible to alternate between zinc-blende (ZB) wurtzite (WZ) crystalline phases, giving origin so called polytypism. This effect has influence in electronic optical properties system, generating new forms confinement carriers. A theoretical model capable accurately describe these polytypical nanostructures...

A systematic numerical investigation of spin-orbit fields in the conduction bands III-V semiconductor nanowires is performed. Zinc-blende (ZB) InSb are considered along [001], [011], and [111] directions, while wurtzite (WZ) InAs studied [0001] $[10\overline{1}0]$ or $[11\overline{2}0]$ directions. Robust multiband $\mathbf{k}\ifmmode\cdot\else\textperiodcentered\fi{}\mathbf{p}$ Hamiltonians solved by using plane-wave expansions real-space parameters. In all cases, linear cubic coupling...

Abstract Definitive evidence for the direct band gap predicted Wurtzite Gallium Phosphide (WZ GaP) nanowires has remained elusive due to lack of strong band-to-band luminescence in these materials. In order circumvent this problem, we successfully obtained large volume WZ GaP structures grown by nanoparticle-crawling assisted Vapor-Liquid-Solid method. With structures, were able observe bound exciton recombination at 2.14 eV with FHWM approximately 1 meV. addition, have measured optical...

p-type \ensuremath{\delta}-doping quantum wells and superlattices are semiconductor systems of considerable interest for basic research device applications. In this paper, a method calculating potentials band structures such is developed. The relies on plane-wave expansion the multiband effective-mass equation, uses kinetic energy matrices any size, takes exchange correlation into account in more rigorous way than was done before. used to calculate potential profiles, subband miniband...

Semiconductor lasers are strongly altered by adding spin-polarized carriers. Such spin could overcome many limitations of their conventional (spin-unpolarized) counterparts. While the vast majority experiments in employed zinc-blende semiconductors, room temperature electrical manipulation was first demonstrated wurtzite GaN-based lasers. However, underlying theoretical description is still missing. To address this situation, focusing on (In,Ga)N-based quantum wells, we develop a framework...

The control of the relative stability between trigonal prismatic and octahedral structures in transition-metal dichalcogenides (TMDs) is an important step toward technological applications 2D TMDs materials, where electronic properties have a strong dependence on structural phase size effects. We report density functional theory investigation effect stoichiometric (MoSe2)n nanoflakes with parallelogram shape for n = 15, 63, 108, 130, 154, 192. found that adopts distorted configuration, which...

Junctions comprised of ferromagnets and nonmagnetic materials are one the key building blocks in spintronics. With recent breakthroughs spin injection ferromagnet/graphene junctions it is possible to consider spin-based applications that not limited magnetoresistive effects. However, for critical studies such structures crucial establish accurate predictive methods would yield atomically resolved information on interfacial properties. By focusing Co(0001)/graphene their electronic structure,...

The k · p method is a successful approach to obtain band structure, optical and transport properties of semiconductors it depends on external parameters that are obtained either from experiments, tight binding or ab initio calculations. Despite the widespread use method, systematic analysis stability accuracy its not usual in literature. In this work, we report theoretical framework determine state-of-the-art hybrid density functional theory including spin–orbit coupling, providing...

The hole-subband and -miniband structures of periodically acceptor $\ensuremath{\delta}$-doped quantum wells superlattices (SL's) in silicon are calculated self-consistently within the effective-mass theory local-density approximation. full six-band Luttinger-Kohn equations solved, together with Poisson equation, a plane-wave representation. Nonparabolicities due to couplings between heavy, light, spin-orbit split bands fully taken into consideration. To account for exchange correlation (XC)...

A general procedure for calculating luminescence spectra from $\ensuremath{\delta}$-doping structures of semiconductors is developed. The electron and hole states are self-consistently calculated within the eight-band Kane model. Explicit results obtained $p$-type wells superlattices in GaAs. For a prototype superlattice (SL) it demonstrated how depend on their self-consistent potentials, band structures, oscillator strengths radiative recombination processes between extended confined...

A long standing problem of solid state theory is solved, being the derivation a set self-consistent one-particle equations for interacting multicomponent hole gas semiconductor in an external potential. Combining effective mass with density functional theory, Hohenberg-Kohn theorem generalized and Kohn-Sham obtained gas. It demonstrated how exchange-correlation potential matrix may be calculated by local approximation. Explicit results are given ${\ensuremath{\gamma}}_{8}$ valence band holes...

The influence of different material parameters, spin-orbit interaction, and strain effects on the valence band structure cubic AlGaN/GaN superlattices is investigated. One-particle hole state calculations are carried out within k⋅p theory by means a full six-band Luttinger-Kohn Hamiltonian in plane-wave representation. It shown that use distinct values for Luttinger parameters barrier well regions leads to significant changes levels, particularly large Al content. Spin-orbit interaction...

Despite the large number of theoretical III-V semiconductor studies reported every year, our atomistic understanding is still limited. The limitations approaches to yield accurate structural and electronic properties on an equal footing, due unphysical self-interaction problem that mainly affects band gap spin-orbit splitting (SOC) in semiconductors and, particular, systems with similar magnitude SOC. In this work, we report a consistent study by using screening hybrid-density functional...

Recent advances in growth techniques have allowed the fabrication of semiconductor nanostructures with mixed wurtzite/zinc-blende crystal phases. Although optical characterization these polytypic structures is well reported literature, a deeper theoretical understanding how phase mixing and quantum confinement change output linear light polarization still needed. In this paper, we theoretically investigate effects wurtzite zinc-blende phases on interband absorption degree an InP...

Hole band structures of p-doped semiconductor heterostructures are presented. The full six-band Luttinger-Kohn Hamiltonian generalized to treat different materials is solved in conjunction with the Poisson equation a plane-wave representation. Self-consistent solutions multiband effective-mass-Poisson equations obtained for unstrained and biaxially strained zinc-blende GaN/InxGa1-xN GaAs/InxGa1-xAs quantum wells superlattices (SLs), which acceptor doping concentration its profile, SL period,...

A self-consistent electronic structure calculation based on the Luttinger-Kohn model is performed $\mathrm{GaMnAs}∕\mathrm{GaAs}$ multilayers. The diluted magnetic semiconductor layers are assumed to be metallic and ferromagnetic. high $\mathrm{Mn}$ concentration (5% in our calculation) makes it possible assume density of moments as a continuous distribution, when treating interaction between holes localized ${\mathrm{Mn}}^{++}$ sites. Within supercell approach we calculated distribution...

In this work we analyze the luminescence emissions from selected isolated GaN/InGaN quantum wells comparing measured and theoretical photoluminescence (PL) spectra. The calculations are performed within k · p method by means of an 8 × Kane Hamiltonian, generalized to treat different materials. Strain effects due large lattice mismatch between InN GaN taken into account. From direct comparison with experimental results, found evidence for transitions involving confined levels which, besides...

We present valence band-structure calculations for undoped and p-doped cubic AlxGa1-xN/GaN superlattices (SLs), in which the coupling between heavy-hole, light-hole, spin-orbit-split-hole bands strain effects due to lattice mismatch are taken into account. The performed within a self-consistent approach k·p theory by means of full six-band Luttinger-Kohn Hamiltonian. Exchange-correlation two-dimensional hole gas included local density approximation. Results minibands potential profiles shown...

In this work we analyze the theoretical photoluminescence (PL) spectra from strained AlGaInN/InGaN and InGaN/AlGaInN superlattices (SLs). The calculations are performed within k.p framework by means of solution 8×8 effective mass Kane Hamiltonian generalized to treat layers different materials. Strain effects due lattice mismatch split-off-hole band were also taken into account. results indicate that PL emissions observed in these systems recombination confined states inside quantum well....