Etude ab-initio des propriétés physiques des composés binaires et ternaires à base de Scandium

Abstract

In this thesis, we presented a theoretical study of the structural, electronic, optical and elastic properties of the compounds Q1-xScxN (Q = B, Al and In) in the two structures Wurtzite and Zinc-blende for (x =0, 0, 0625, 0.125, 0.1875, 0.25, 0.375, 0.5). The calculations were carried out by the method of calculating the pseudo-potential plane waves (PP-PW) implemented in the CASTEP code which is based on the theory of the density functional (DFT) using the GGA approximation. The calculation of the band structure shows that the Q1-xScxN alloys have a direct band gap.On the other hand, we have calculated the density of total and partial states (DOS and PDOS) of the three compounds BN, AlN and InN, and their alloys Q1- xScxN, the optical properties (ℇ1(), ℇ2(), n(), k(), α(), R() and L() ) and the elastic constants (Cij, B, G, E, υ and B/G) and the longitudinal and shear wave velocities (Vl, Vs) and Debye temperature θD. The results obtained by the simulation are in good agreement with the experimental and theoretical results available and on the other hand they constitute a reliable prediction for any future experimental work for these materials. .