M. Boujnah

Optoelectronic response of spinels CdX2O4 with X = (Al, Ga, In) through the modified Becke–Johnson functional

Structural, electronic, and optical properties of CdAl2O4, CdGa2O4, and CdIn2O4 are investigated using the first principles technique based on the new potential approximation known as the Tran–Blaha modified Becke–Johnson exchange potential approximation (TB-mBJ). We discuss the improvements in the band gap determination using TB-mBJ compared to the standard generalized gradient approximation in density functional theory. The calculated equilibrium lattice parameters are in reasonable agreement with the experimental results. Electronic properties have been studied through the calculation of band structure and density of states. Based on our electronic structure obtained using the mBJ method, we have calculated various optical properties, including the complex dielectric function e(ω), complex index of refraction n(ω), reflectivity coefficient R(ω), absorption coefficient α(ω), and the electron energy-loss function L(ω) as functions of the photon energy. We chose these three representative oxides spinel du...

Understanding ferromagnetism and optical absorption in 3d transition metal-doped cubic ZrO2 with the modified Becke-Johnson exchange-correlation functional

The electronic structure, magnetic, and optical properties in cubic crystalline phase of Zr1−xTMxO2 (TM = V, Mn, Fe, and Co) at x = 6.25% are studied using density functional theory with the Generalized Gradient Approximation and the modified Becke-Johnson of the exchange-correlation energy and potential. In our calculations, the zirconia is a p-type semiconductor and has a large band gap. We evaluated the possibility of long-range magnetic order for transition metal ions substituting Zr. Our results show that ferromagnetism is the ground state in V, Mn, and Fe-doped ZrO2 and have a high value of energy in Mn-doped ZrO2. However, in Co-doped ZrO2, antiferromagnetic ordering is more stable than the ferromagnetic one. The exchange interaction mechanism has been discussed to explain the responsible of this stability. Moreover, it has been found that the V, Mn, and Fe transition metals provide half-metallic properties considered to be the leading cause, responsible for ferromagnetism. Furthermore, the optical...

New transparent conducting oxide based on doped SnO 2 for solar cells

The full-potential linearized augmented plane wave method (FP-LAPW) based on the density functional theory (DFT) and Boltzmanns Transport theory, are employed to investigate theoretically the electronic structure, optical and electrical properties of Sc, Ti and V doped rutile SnO2. The FP-LAPW based on the new potential approximation known as the Tran-Blaha modified Becke-Johnson exchange potential approximation (mBJ). The calculated band structure and density of states (DOS) exhibit a band gap of pure SnO2 (3.3 eV) closer to the experimental one. As well, our results indicate that the average transmittance in the 400 to 1000 nm wavelength region was 90%. The high transmittance and electrical conductivity indicate that doped SnO2 system is a potential as material for solar energy applications.

Electronic structure, optical and magnetic properties of Zn 1−x M x Te (M = Ti, Cr and Mn) Ab initio calculations

Optical and electronic properties of zinc blende ZnTe bulk and doped with transition metals (Ti, Cr and Mn) have been calculated using a Full Potential Augmented Plane Wave (FP-LAPW) method within the density functional theory. The exchange-correlation potential was treated with the Generalized Gradient Approximation (GGA) to calculate the total energy. For the electronic and optical properties calculations, the exchange and correlation effects were treated by the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential to prevent the inconvenience of the underestimation of the energy gaps in GGA. The obtained results are compared to available experimental data and to other theoretical calculations.