Norbert Janik
Wroclaw University of Science and Technology, Poland
Title: The effect of strains on electronic structures of group IV diamond like crystals – DFT based studies
Biography
Biography: Norbert Janik
Abstract
Materials composed of the group IV elements are promising candidates for designing the nano-optoelectronic devices integrated with Si based circuits. Special requirements concerning the electronic properties of the materials (direct band-gap, high mobility of carriers) can be met via the electronic structure engineering. One of methods of modifying the electronic structure is applying the strain [1, 2, 3], e.g. by the choice of unmatched lattices in epitaxial technologies. In this work the DFT based computational methods have been applied to investigate systematically the effect of strains on electronic structure, with the use of ABINIT program. In reference to available technologies the isotropic as well as uniaxial and biaxial strains for crystallographic planes (100), (110) and (111) in diamond like crystals of C, Si, Ge and Sn have been studied. The systems were strained in the range of +/–4%. The following characteristics have been evaluated as functions of the strain: Poison’s ratios, elastic coefficients, band gaps in between chosen band structure points and band offsets. A detailed discussion of observed effects (considering also the orbital composition of bands) such as indirect direct gap transition, opening/closing the gaps, strain induced symmetry breaking effect and band offsets, the effect of lowering the band gap on electron mobility, will be presented.