Laboratoire Sciences des Matériaux et Applications

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    Improvement electronic and magnetic properties of Cr impurity doped PbSe for optoelectronic devices applications: a first-principles proposal
    (THE EUROPEAN PHYSICAL JOURNAL B, 2021) Benkada, Amel; Habri, Salem; Bouzouira, Nour Eddine; Bensaid, Djillali; Hamli, Meryem; Bencherif, Kaddour
    To produce innovative spintronics components, we are now looking for ferromagnetic semiconductors at room temperature. The aim of this work is to study the electronic structures and the magnetic properties is to trigger ferromagnetism and to improve the band gap of PbSe The study of the electronic structure and the magnetic properties of diluted magnetic semiconductors (DMS) type IV–VI PbSe doped Cr is investigated in detail. Our results are as follows. We then calculated the sp-d exchange couplings between electrons (holes) of the conduction (valence) band and magnetic impurities. The topology of the band structure shows that our material is half metal, which has a direct gap in the minority channel due to the nature of sp–d coupling. The values of Nα ferromagnetic and Nβ antiferromagnetic obtained in the mean-field approximation are of the order of 0.551 and −0.445 eV respectively. The Thermoelectric Conversion Efficiency focuses on a single dimension parameter, the figure of merit ZT. We have seen that doping with Cr can also have a beneficial effect on thermal conductivity and consequently on ZT. This leads our material among the best compounds to thermoelectric applications.
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    First principle investigation of physical properties of MNiBi: (M = Sc, Y) half-Heusler compounds
    (2022) Missoum, D.-E; Bencherif, K; Bensaid, D
    We have investigated the half Heusler compounds MNiBi (M=Sc, Y), using the framework of density functional theory DFT within the full potential linearized augmented plane wave (FP-LAPW) method and studied the structural, electronic, optical and elastic properties. The structural properties are predicted using the Generalized Gradient Approximation GGA and Local Density Approximation LDA, the calculations reveal that Lattice constants and other structural parameter are better matched in GGA approximation with experimental and theoretical result than LDA approximation. The calculated band structure and the density of states (DOS) with GGA, LDA and Tran and Blaha modified Becke-Johnson (TB-mBJ) exchange-correlation potentials, indicates a semiconducting nature with indirect narrow band gaps for both compounds ScNiBi and YNiBi, it shown from result that using (TB-mBJ) functionals is much more successful than the LDA and GGA approach in estimating bandgaps for our half Heusler ScNiBi and YNiBi. Optical properties of the compounds under investigation are also reported in this paper, high absorptivity are observed in the visible and ultraviolet region. The bulk modulus, shear modulus, young’s modulus, and other elastic constants are computed to discuss their elastic properties
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    n-type SnS2 thin films spray-coated from transparent molecular ink as a non-toxic buffer layer for solar photovoltaics
    (2022) Tair, Sabrina; Ghediya, Prashant R; Nebatti Ech-Chergui, Abdelkader; Guezzou, M’hamed; Kumar Mukherjee, Sanat; Driss-Khodja, Kouider; Singh, Rajan; Ray, Jaymin; Bouhalouane, Amrani
    This paper reports the effect of solvent evaporation temperature on spray-coated tin disulfide (SnS2) thin films from molecular ink. Thiourea and tin chloride were the key chemical reagents used for the synthesis of SnS2 transparent ink under atmospheric conditions. The structural and compositional properties of SnS2 thin films revealed formation of pristine hexagonal SnS2. The films are smooth, homogeneous resulting in band gaps ranging from 2 to 2.22 eV suited for a Cd-free alternative buffer layer for Cu-based multicomponent solar cells. Thermoelectric power measurement showed that tin disulfide films exhibit n-type conductivity. Activation energy estimated from temperature variation of electrical conductivity measurement varied from 40 to 90 mV. Our results suggest that ink-processed SnS2 can be used as a potential alternative for opto-electronic devices such as thin film solar cell and photodetector devices
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    Exchange-correlation and spin-orbit coupling effects in 18-electrons transparent conductors half-Heusler: Ab-initio study
    (Elsevier, 2022) Mellah, Djallal Eddine; Demmouche, Kamel
    The structural and electronic properties of a two non-oxide Transparent Conductors (TC’s), Ir-based halfHeusler XIrSb (X = Ti,Zr) are studied using DFT based on plane waves pseudo potential method. We examined two aspects: (i) the effect of the exchange–correlation (XC) approximation, namely: PBE, PBE+U and meta-GGA SCAN (The strongly constrained and appropriately normed); and (ii) the spin–orbit coupling (SOC) effects of the heavy metals on these compounds. We found that: (i) SCAN, similar to PBE+U, yields larger band gap compared to the PBE corresponding values for both compounds. SCAN gives a band gap about halfway between PBE and experiment or Hybrid-GGA. Similarly to PBE and PBE+U, SCAN shows the semiconducting behavior of the compounds with indirect band gap at the same locations in Brillouin Zone; (ii) spin–orbit coupling causes an important splitting in the valence band maximum (VBM) of order 0.44 eV and 0.58 eV for TiIrSb and ZrIrSb respectively leading to reduction of the band gap. Thus, the heavier is the X atom the larger is the SOC splitting. The VBM is dominated by 𝐽𝑒𝑓𝑓 = 3∕2 state. However, the splitting is almost negligible on the conduction band minimum (CBM). Therefore, SOC is crucial for predicting the band gap and reproducing correctly the electronic structure of these compounds.