Browsing by Author "Akyuz, G. Bilgec"

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First-Principles Calculations of Structural and Electronic Properties of Tlxga1-Xas Alloys
(Iop Publishing Ltd, 2016) Akyuz, G. Bilgec; Tunali, A. Y.; Gulebaglan, S. E.; Yurdasan, N. B.
The zincblende ternary alloys TlxGa1-xAs (0 < x < 1) are studied by numerical analysis based on the plane wave pseudopotential method within the density functional theory and the local density approximation. To model the alloys, 16-atom supercells with the 2 x 2 x 2 dimensions are used and the dependency of the lattice parameter, bulk modulus, electronic structure, energy band gap, and optical bowing on the concentration x are analyzed. The results indicate that the ternary TlxGa1-xAs alloys have an average band gap bowing parameter of 4.48 eV for semiconductor alloys and 2.412 eV for semimetals. It is found that the band gap bowing strongly depends on composition and alloying a small Tl content with GaAs produces important modifications in the band structures of the alloys.
Structural and Electronic Properties of Gaxtl1-Xp Ternary Alloys
(Elsevier Sci Ltd, 2015) Tunali, A. Yildiz; Gulebaglan, S. Erden; Yurdasan, N. Boz; Akyuz, G. Bilgec
The structural and electronic properties of GaxTl1-xP ternary alloys in zincblende phase were studied using pseudopotential plane wave method within the density functional theory. The dependence of the lattice parameter, bulk modulus, its pressure derivative, electronic structure, energy band gap and optical bowing on the composition x were analyzed for 0 < x < 1 with small increments, disregarding the so long computational time. The lattice parameters were optimized exhibiting linear concentration dependence in accordance with Vegard's law. The bulk modulus as a function of gallium composition shows linear-like concentration dependence with a large upward bowing parameter equal to 10.79 GPa. We found that the band gap increases with increasing compositions of Ga, so that the compounds change from metal to semiconducting phase and could be useful for device applications in spintronics, especially at certain contributions. As a consequence the band gap bowing is found to be strongly composition dependent. The microscopic origins of the gap bowing were detailed and explained according to Zunger approach. (C) 2015 Elsevier Ltd. All rights reserved.