PUBLICATIONS SCIENTIQUES ET PEDAGOGIQUES

Permanent URI for this community

http://172.16.16.5:4000/handle/123456789/363

Browse

Browsing PUBLICATIONS SCIENTIQUES ET PEDAGOGIQUES by Author "BENOUDIA Mohamed Cherif (Co-Auteur)"

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Direct Observations of the Structural Properties of Semiconducting Polymer: Fullerene Blends under Tensile Stretching
    (Materials, 2020-07-10) ALIOUAT Mouaad Yassine; BENOUDIA Mohamed Cherif (Co-Auteur)
    We describe the impact of tensile strains on the structural properties of thin films composed of P BT4T-2OD -conjugated polymer and PC71BM fullerenes coated on a stretchable substrate, based on a novel approach using in situ studies of flexible organic thin films. In situ grazing incidence X-ray di raction (GIXD) measurements were carried out to probe the ordering of polymers and to measure the strain of the polymer chains under uniaxial tensile tests. A maximum 10% tensile stretching was applied (i.e., beyond the relaxation threshold). Interestingly we found di erent behaviors upon stretching the polymer: fullerene blends with the modified polymer; fullerene blends with the 1,8-Diiodooctane (DIO) additive. Overall, the strain in the system was almost twice as low in the presence of additive. The inclusion of additive was found to help in stabilizing the system and, in particular, the – packing of the donor polymer chains.
  • Thumbnail Image
    Item
    Equiaxed grain structure formation during directional solidification of a refined Al-20wt.%Cu alloy: In situ analysis of temperature gradient effects
    (Journal of Crystal Growth, 2022-03-27) SOLTANI Hadjer; BENOUDIA Mohamed Cherif (Co-Auteur)
    Three series of directional solidification experiments on refined Al-20wt.%Cu alloys have been carried out with different temperature gradients, and for each of them a wide range of cooling rates were applied. The experiments were performed in horizontal configuration to minimize the impact of gravity-driven phenomena and characterized in situ and in real-time by using the X-radiography technique. The influence of the temperature gradient on the microstructure formation (impact of Temperature Gradient Zone Melting: TGZM), the nucleation distance, the average grain size and morphology (elongation factor and grain orientation) have been analysed quantitatively. The experimental results are discussed with current theoretical models and similar experimental works.
  • Thumbnail Image
    Item
    Ge(Sn) growth on Si(001) by magnetron sputtering
    (Materials Today Communications, 2020-11-26) BENOUDIA Mohamed Cherif (Co-Auteur)
    The semi-conductor Ge1–xSnx exhibits interesting properties for optoelectronic applications. In particular, Ge1–xSnx alloys with x ≥ 0.1 exhibit a direct band-gap, and integrated in complementary-metal-oxide semiconductor (CMOS) technology, should allow the development of Si photonics. CMOS-compatible magne tron sputtering deposition was shown to produce monocrystalline Ge1–xSnx films with good electrical properties at low cost. However, these layers were grown at low temperature (< 430 K) and contained less than 6 % of Sn. In this work, Ge1–xSnx thin films were elaborated at higher temperature (> 600 K) on Si(001) by magnetron sputtering in order to produce low-cost and CMOS-compatible relaxed pseudo-coherent layers with x ≥ 0.1 exhibiting a better crystallinity. Ge1–xSnx crystallization and Ge1–xSnx crystal growth were investigated. Crys tallization of an amorphous Ge1–xSnx layer deposited on Si(001) or Ge(001) grown on Si(001) leads to the growth of polycrystalline films. Furthermore, the competition between Ge/Sn phase separation and Ge1–xSnx growth prevents the formation of large-grain Sn-rich Ge1–xSnx layers without the formation of β-Sn islands on the layer surface, due to significant atomic redistribution kinetics at the crystallization temperature (T = 733 K for x = 0.17). However, the growth at T = 633 K of a highly-relaxed pseudo-coherent Ge0.9Sn0.1 film with low impurity concentrations (< 2 × 1019 at cm–3 ) and an electrical resistivity four orders of magnitude smaller than undoped Ge is demonstrated. Consequently, magnetron sputtering appears as an interesting technique for the integration of optoelectronic and photonic devices based on Ge1–xSnx layers in the CMOS technology.