Resumo

SALCEDO-REYES, Juan Carlos. Electronic band structure of the ordered Zn_0.5Cd_0.5Se alloy calculated by the semi-empirical tight-binding method considering second-nearest neighbor. Univ. Sci. [online]. 2008, vol.13, n.2, pp.198-207. ISSN 0122-7483.

Usually, semiconductor ternary alloys are studied via a pseudo-binary approach in which the semiconductor is described like a crystalline array were the cation/anion sub-lattice consist of a random distribution of the cationic/anionic atoms. However, in the case of reported III-V and II-VI artificial structures, in which an ordering of either the cations or the anions of the respective fcc sub-lattice is involved, a pseudo-binary approach can no longer be employed, an atomistic point of view, which takes into account the local structure, must be used to study the electronic and optical properties of these artificial semiconductor alloys. In particular, the ordered Zn_0.5Cd_0.5Se alloy has to be described as a crystal with the simple-tetragonal Bravais lattice with a composition equal to the zincblende random ternary alloy. The change of symmetry properties of the tetragonal alloy, in relation to the cubic alloy, results mainly in two effects: i) reduction of the banned gap, and ii) crystal field cleavage of the valence band maximum. In this work, the electronic band structure of the ordered Zn_0.5Cd_0.5Se alloy is calculated using a second nearest neighbor semi-empirical tight binding method. Also, it is compared with the electronic band structure obtained by FP-LAPW (fullpotential linearized augmented-plane wave) method.

Palavras-chave : band gap narrowing; electronic band structure; ordered alloys; Semi-empirical thigh binding method; ZnCdSe alloy.

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