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arXiv 1002.4827cond-mat.mtrl-sci
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复杂透明导电氧化物的性能调节:晶体对称性、化学组成和载流子产生的作用

Tuning the properties of complex transparent conducting oxides: role of crystal symmetry, chemical composition and carrier generation

Julia E. Medvedeva, Chaminda L. Hettiarachchi

摘要:

采用第一性原理密度泛函方法研究了单阳离子和多阳离子透明导电氧化物的电子性质。化学计量的和缺氧的In $_2$ O $_3$、$α$ -和$β$ $_2$ O $_3$、岩盐和纤锌矿ZnO、以及层状InGaZnO $_4$的电子能带结构的详细比较揭示了控制这些TCO材料的传输和光学性质的以下因素的作用:(i)氧化物的晶体对称性,包括氧配位和长程结构各向异性;(ii)阳离子的电子构型,特别是形成导带的轨道类型-- $s$、$p$或$d$;以及(iii)阳离子状态和相邻氧原子的p-状态之间的杂化强度。结果不仅解释了实验观察到的单阳离子TCO的电导率的趋势,但也表明,多组分氧化物可以提供一种方法来克服电子局域化的瓶颈,限制了在宽带隙主族金属氧化物的电荷传输。此外,异价替代掺杂的优点-在TCO主机中产生载流子的替代途径-概述了基于Sn,Ga,Ti和Zr掺杂的InGaZnO $_4$的电子能带结构计算。我们表明,过渡金属掺杂剂提供了在不影响光学透射率的情况下提高导电性的可能性。

英文摘要:

The electronic properties of single- and multi-cation transparent conducting oxides (TCOs) are investigated using first-principles density functional approach. A detailed comparison of the electronic band structure of stoichiometric and oxygen deficient In$_2$O$_3$, $α$- and $β$-Ga$_2$O$_3$, rock salt and wurtzite ZnO, and layered InGaZnO$_4$ reveals the role of the following factors which govern the transport and optical properties of these TCO materials: (i) the crystal symmetry of the oxides, including both the oxygen coordination and the long-range structural anisotropy; (ii) the electronic configuration of the cation(s), specifically, the type of orbital(s) -- $s$, $p$ or $d$ -- which form the conduction band; and (iii) the strength of the hybridization between the cation's states and the p-states of the neighboring oxygen atoms. The results not only explain the experimentally observed trends in the electrical conductivity in the single-cation TCO, but also demonstrate that multicomponent oxides may offer a way to overcome the electron localization bottleneck which limits the charge transport in wide-bandgap main-group metal oxides. Further, the advantages of aliovalent substitutional doping -- an alternative route to generate carriers in a TCO host -- are outlined based on the electronic band structure calculations of Sn, Ga, Ti and Zr-doped InGaZnO$_4$. We show that the transition metal dopants offer a possibility to improve conductivity without compromising the optical transmittance.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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