Strong dependence of the fundamental band gap on the alloy composition in cubic In x Ga 1-x N and In x Al 1-x N alloys
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Strong dependence of the fundamental band gap on the alloy composition in cubic InxGa1-xN and InxAl1-xN alloys Z. Dridi 1, 2, B. Bouhafs 2, and P. Ruterana 1 1 SIFCOM, UMR6176, CNRS-ENSICAEN, 6, Bld Maréchal Juin, 1450 Caen, France 2 Modelling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, 22000 Sidi Bel-Abbes, Algeria. ABSTRACT Ab initio total energy calculations, based on the full-potential augmented plane wave method within the local density approximation, are used to study the influence of alloying on the structural and electronic properties of cubic InxGa1-xN and InxAl1-xN ordered alloys in the chalcopyrite and luzonite structures. We have investigated the lattice parameters and band gap energies. The lattice parameters, exhibit an upward bowing of -0.05 Å and -0.15 Å, respectively for the InxGa1-xN and InxAl1-xN alloys. The composition dependence of the band gap shows a bowing parameter of 1.36 eV for InxGa1-xN. The band gap InxAl1-xN alloys exhibits a bowing parameter of 3.19 eV, and a direct to indirect band gap transition at x (Al) = 0.83. The large bowing effect in InxAl1-xN alloys has been discussed in terms of a composition dependent bowing parameter.
INTRODUCTION The III nitrides GaN, InN, and AlN crystallize in the wurtzite structure and are characterized by direct fundamental gaps of 3.4 eV [1] (GaN),
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