CMT & EMAT, Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
J Phys Condens Matter. 2013 Oct 16;25(41):415503. doi: 10.1088/0953-8984/25/41/415503. Epub 2013 Sep 24.
We present an ab initio study of the electronic structure and of the formation energies of various point defects in BaSnO3 and SrGeO3. We show that La and Y impurities substituting Ba or Sr are shallow donors with a preferred 1 + charge state. These defects have a low formation energy within all the suitable equilibrium growth conditions considered. Oxygen vacancies behave as shallow donors as well, preferring the 2 + charge state. Their formation energies, however, are higher in most growth conditions, indicating a limited contribution to conductivity. The calculated electron effective mass in BaSnO3, with a value of 0.21 m(e), and the very high mobility reported recently in La-doped BaSnO3 single-crystals, suggest that remarkably low scattering rates can be achieved in the latter. In the case of SrGeO3, our results point to carrier density and mobility values in the low range for typical polycrystalline TCOs, in line with experiment.
我们进行了一项从头算研究，研究了 BaSnO3 和 SrGeO3 中各种点缺陷的电子结构和形成能。我们表明，替代 Ba 或 Sr 的 La 和 Y 杂质是浅施主，优先具有 1+电荷态。在考虑的所有合适的平衡生长条件下，这些缺陷的形成能都很低。氧空位也表现为浅施主，更喜欢 2+电荷态。然而，它们的形成能在大多数生长条件下较高，表明对电导率的贡献有限。在 BaSnO3 中计算出的电子有效质量为 0.21 m(e)，以及最近在 La 掺杂 BaSnO3 单晶中报道的极高迁移率，表明在后一种情况下可以实现非常低的散射率。在 SrGeO3 的情况下，我们的结果表明载流子密度和迁移率值在典型的多晶 TCO 的低值范围内，与实验结果一致。
