In this paper, we have calculated the optical properties of the different polytypes of GaSe lamellar materials. The calculations are based on the DFT method and is performed using the CASTEP code. All optical properties have been studied in a domain that extends energetically from 10 meV to 35eV and have been measured for a polarization // and ⊥ with the c axis. A strong anisotropic was observed, which indicates that the optical properties of the GaSe material are essentially determined by the symmetry of a single layer, exactly by the symmetry resulting from the stacking of the layers. The study of the optical properties of the semiconductor GaSe, shows anisotropic optical behavior. In addition, the absorption starts in the UV-Visible spectral range, the peaks appear in the UV range, which is important for photovoltaic applications. Our results are important and give a great chance to these lamellar materials for wide use and various applications.
We investigated the effect of the hydrostatic pressure on the optoelectronic properties of a quantum well (QW) based on δ-doped GaAs sandwiched by Ga1-xAlxAs. We study the case of a non-parabolic conduction band where the aluminum content is set at 30%. We perform our calculations in the context of the approximation of the envelope function formalism using the finite difference method. Results show that the transition energies decrease with the increase of the hydrostatic pressure, which causes remarkable modifications on the optical properties of the QW nanostructure. The non-parabolicity effect is more important for small QW (Lw ≤ 5nm) and less marked in narrow and large QW. In addition, we study the absorption coefficient for 8 nm/4 nm/8 nm geometry. On the one hand, the pressure increase creates a displacement of the optical absorption coefficient towards low energies and a decrease of the absorption peak value. On the other hand, the refractive index moves towards higher energies. We show that in the presence of a hydrostatic pressure and following its effect on intersubband transitions, these optical properties also depend on the dopant concentration rate and the quantum well width. Our study finds interests for the nano-fabrication of quantum wells and in particular for those used in optical and electronic applications.
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