Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 92: Poster Session: Structure and transport in organic photovoltaics; Photovoltaics; Impurities/Amorphous semiconductors; New materials

HL 92.19: Poster

Donnerstag, 14. März 2013, 16:00–20:00, Poster A

Formation energy of point defects with transition metal (TM = Cr, Mn and Fe) doped barium titanate from first-principles studies — Sanjeev K. Nayak¹, •Waheed A. Adeagbo¹, Hans T. Langhammer², and Wolfram Hergert¹ — ¹Institute of Physics, Martin Luther University Halle-Wittenberg, Von-Seckendorff-Platz 1, 06120 Halle, Germany — ²Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 2, 06120 Halle, Germany

We study the electronic properties of substitutional doped transition metal (TM = Cr, Mn and Fe) in barium titanate from the first-principles studies. We explore the stability of different valency states for the TM dopants which are probabilistic in experimental conditions. For such a consideration, we have modeled the system by charged supercells and also by possible charge compensation mechanism through the presence of oxygen vacancy (V_O). The analysis on the stability of defects is done by comparing the formation energy of defects. The regular expression of the Zhang-Northrup formulation for the formation energy of charge defects is used in our calculation together with the band gap correction. We use the Vienna ab initio simulation package (VASP). The supercell consists of 3×3×1 periodic repetition of hexagonal BaTiO₃ unit cell, which is the crystal structure of about 2 mol% TM-doped material at room temperature and normal pressure, and constitute of 54 functional units of BaTiO₃ where one Ti ion is substituted by a TM ion. Thus the defect concentration we are dealing with is about 1.85 mol% and this is in the range of experimental limits.