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Computer simulation of nonequilibrium states of gallium arsenide nanolayer doped by atoms of manganese

Serge A. Beznosyuk 1Mark S. Zhukovskiy 2Yuliya V. Zemtsova 1Larisa V. Fomina 3

1. Altai State University (ASU), Lenin St., 61, Barnaul 656049, Russian Federation
2. Altai State Technical University (ASTU), Lenin st.46, Barnaul 656038, Russian Federation
3. Angarsk State Technical Academy (ASTA), Tchaikovsky str., 60, Angarsk 665835, Russian Federation


It is well-known that alloying of Mn atoms into gallium arsenide is capable to provide transition of a material to a ferromagnetic state with relatively high Curie point on preservation of the basic semi-conductor parameters as the result of its zoned structure change. That brings the given compound to a perspective spintronics material. But there is a problem. At achievement of concentration of the impurity over 5 % the lattice of the compound loses the stability. Some researchers supposed that the reason of this instability is nucleation of local crystal structure of manganese arsenide, which essentially differs from an initial lattice of gallium arsenide. The purpose of presented work is a simulation of this nanostructure instability of gallium arsenide nanolayer system doped by atoms of manganese. Using a crystal lattice data initial GaAs nanolayer structure of 20x20x2 elementary cells with total number of 6400 atoms was constructed. Alloying of gallium arsenide nanolayer was fulfilled by the replacement of gallium atoms with 100, 200, 248, 264, 288, 320, 400 atoms of manganese. It corresponds to small concentration of Mn impurity. After that variation procedure of energy minimization was used by nonlocal density functional method. The nanostructure optimization by algorithmic steepest descent method along the binding potential energy surface in a configuration space of nanosystem was performed. The basic results of the computer experiment were as following. 1. At alloying impurity manganese atoms are homogeneously distributed in a diamondlike lattice of gallium arsenide. 2 Increasing concentration of the impurity multiplies the probability of occurrence in an initial lattice of the semiconductor of local fluctuations when four atoms of manganese occupy the first coordination sphere of arsenide atom. In this place there is a local instability of nanostructure and as result lattice distortions the local fragment of a crystal lattice of manganese arsenide arises.


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Presentation: Oral at E-MRS Fall Meeting 2009, Symposium E, by Serge A. Beznosyuk
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-05 15:33
Revised:   2009-06-07 00:48