Eur. Phys. J. B (2017) 90: 103
https://doi.org/10.1140/epjb/e2017-70724-5

Regular Article

First principle calculations of iron and iron-boron transition levels in Si_1−xGe_x alloy

¹ Taibah University, College of Science, Department of Physics, Yanbu-branch, Yanbu, Saudi Arabia
² Aix-Marseille Université, CNRS, IM2NP UMR7334, 13397 Marseille Cedex 20, France

^a e-mail: mkhalfalla@taibahu.edu.sa

Received: 9 December 2016
Received in final form: 25 February 2017
Published online: 5 June 2017

Abstract

This paper investigates, using first principle calculations, the charge transition levels Fe^0/+ and FeB^0/+, and the FeB binding energy in Si_1−xGe_x alloy with composition x = 3 − 25%. The alloys were generated using an efficient code for the stochastic generation of special quasirandom structures. We found that the separation between Fe^0/+ and FeB^0/+ donor levels was ~0.24 eV (experimental value =0.28 eV) and was independent on x, in an agreement with the experiment. The pattern of the variation of the levels and band gap energies with x agreed very well with the experiment especially for x< 25 %. The formation of FeB-pairs was found to be favorable over individual Fe formation with average binding energy ~0.2 eV, agreeing with the first-principle calculation report using finite supercell size. In particular, the reliability of our method to reproduce the experimental results associated with the composition controlled FeB donor levels has successfully been demonstrated in the industrially interesting SiGe alloy material.