Abderrezak Belabbes

Electronic bands of III-V semiconductor polytypes and their alignment

The quasiparticle band structures of four polytypes 3C, 6H, 4H, and 2H of GaP, GaAs, GaSb, InP, InAs, and InSb are computed with high accuracy including spin-orbit interaction applying a recently developed approximate calculation scheme, the LDA-1/2 method. The results are used to derive band offsets

Structure, energetics, and electronic states of III-V compound polytypes.

\ensuremath{\Delta}{E}_{c}

Direct experimental determination of the spontaneous polarization of GaN

and

Hund’s Rule-Driven Dzyaloshinskii-Moriya Interaction at 3d-5d Interfaces

\ensuremath{\Delta}{E}_{v}

Oxygen-enabled control of Dzyaloshinskii-Moriya Interaction in ultra-thin magnetic films.

for the conduction and valence bands between two polytypes. The alignment of the band structures is based on the branch-point energy

Correlation of the Dzyaloshinskii–Moriya interaction with Heisenberg exchange and orbital asphericity

{E}_{\mathrm{BP}}

Electronic properties of polar and nonpolar InN surfaces: A quasiparticle picture

for each polytype. The aligned electronic structures are used to explain properties of heterocrystalline but homomaterial junctions. The gaps and offsets allow to discuss spectroscopic results obtained recently for such junctions in III-V nanowires.

Polytypism in ZnS, ZnSe, and ZnTe: First-principles study

Recently several hexagonal polytypes such as 2H, 4H, and 6H have been discovered for conventional III-V semiconductor compounds in addition to the cubic 3C zinc-blende polytype by investigating nanorods grown in the [111] direction in different temperature regimes. Also III-mononitrides crystallizing in the hexagonal 2H wurtzite structure under ambient conditions can be deposited in zinc-blende geometry using various growth techniques. The polytypic crystal structures influence the local electronic properties and the internal electric fields due to the spontaneous polarization in non-cubic crystals.In this paper we give a comprehensive review on the thermodynamic, structural, and electronic properties of twelve Al, Ga, and In antimonides, arsenides, phosphides, and nitrides as derived from ab initio calculations. Their lattice parameters, energetic stability, and characteristic band structure energies are carefully discussed and related to the atomic geometries of the polytypes. Chemical trends are investigated. Band offsets between polytypes and their consequences for heterocrystalline structures are derived. The described properties are discussed in the light of available experimental data and previous computations. Despite several contradictory results in the literature, a unified picture of the III-V polytypes and their heterocrystalline structures is developed.

Relation between spontaneous polarization and crystal field from first principles

We present a universal approach for determining the spontaneous polarization Psp of a wurtzite semiconductor from the emission energies of excitons bound to the different types of stacking faults in these crystals. Employing micro-photoluminescence and cathodoluminescence spectroscopy, we observe emission lines from the intrinsic and extrinsic stacking faults in strain-free GaN micro-crystals. By treating the polarization sheet charges associated with these stacking faults as a plate capacitor, Psp can be obtained from the observed transition energies with no additional assumptions. Self-consistent Poisson-Schroedinger calculations, aided by the microscopic electrostatic potential computed using density-functional theory, lead to nearly identical values for Psp. Our recommended value for Psp of GaN is -0.022+/-0.007 C/m^{2}.

k-asymmetric spin-splitting at the interface between transition metal ferromagnets and heavy metals.

Using relativistic first-principles calculations, we show that the chemical trend of the Dzyaloshinskii-Moriya interaction (DMI) in 3d-5d ultrathin films follows Hunds first rule with a tendency similar to their magnetic moments in either the unsupported 3d monolayers or 3d-5d interfaces. We demonstrate that, besides the spin-orbit coupling (SOC) effect in inversion asymmetric noncollinear magnetic systems, the driving force is the 3d orbital occupations and their spin-flip mixing processes with the spin-orbit active 5d states control directly the sign and magnitude of the DMI. The magnetic chirality changes are discussed in the light of the interplay between SOC, Hunds first rule, and the crystal-field splitting of d orbitals.