Browsing by Author "L. Radjehi"

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    Effect of vacuum annealing on the structural and optical properties of sputtered Cu4O3 thin films
    (2020-04-29) L. Radjehi
    Cu4O3 thins films were deposited by the reactive magnetron sputtering process on glass and Si (100) wafers. In order to investigate the thermal stability of the Cu4O3 phase, the films were subjected to vacuum annealing treatment for one hour at various temperatures ranging from 200°C to 500°C. The samples were characterized by using EDS, XRD, SEM and UV–VIS. The phase transformation of Cu4O3 into Cu2O was obtained from 300°C (critical temperature). Increasing annealing temperature leads to compact morphology and the grain shape changing from elongated towards spherical. Due to this annealing the film structure presentes coexistence of a Cu4O3 and Cu2O mixture where O atoms are lost in the Cu–O system. The UV–VIS analysis reveals a gradual increase in the transmittances from 55 to 70% with the increasing annealing temperature, while the band gap shows a maximum value (Eg = 2 eV) at 500°C corresponding to the Cu2O phase.
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    Structural and magnetic properties of copper oxide films deposited by DC magnetron reactive sputtering
    (2018-10-01) L. Radjehi
    Copper oxide films have been successfully deposited onto glass/Si(100) substrates by DC reactive magnetron sputtering in Ar/O 2 gas mixtures, while varying oxygen flow rate. The obtained results based on the structure and magnetic properties are discussed. Depending on the oxygen flow rate, the films reveal different phases and morphologies of Cu2O, Cu4O3 and CuO. In addition, the magnetic properties of the copper oxides thin films are found to be strongly influenced by the oxygen flow rate; the ferro–para transition is influenced by the formation/cancellation of point defects.