Abstract A transparent conducting oxide (TCO) thin film exhibits a very high electrical conductivity and high visible light transparency with considerable practical applications in solar cells and in transparent electronics. As a promising substitute to Sn-doped In2O3 (ITO), doped ZnO thin films are widely considered due to low-cost, non-toxicity and high durability against the H plasma compared with ITO. In this review, by ‘co-doping', we mean cation-cation (two iso-valent or heterovalent cations) and cation-anion (one higher valence cation and one lower valence anion) double doping in ZnO film. This article commences with a generalized description of TCOs, ITO and single-doped ZnO followed by a discussion on co-doped ZnO. We systemically present the current progress in both co-doping studies with critically summarized results to gain an overview, especially regarding the electrical properties. The cation-cation co-doping results in a wide range of carrier concentrations and resistivity values due to the competitive Zn site substitution by two different cations simultaneously. Cation-anion co-doping leads to an expected change in the carrier concentration and resistivity values with a higher mobility in general due to fewer lattice defects. Finally, the article concludes with a brief discussion on problems and challenges to be addressed in the near future.

中文翻译：

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重新审视作为 n 型 TCO 的共掺杂 ZnO 薄膜的电和光传输特性

摘要 透明导电氧化物 (TCO) 薄膜表现出非常高的导电性和高可见光透明度，在太阳能电池和透明电子产品中有相当多的实际应用。作为 Sn 掺杂的 In2O3 (ITO) 的有前途的替代品，掺杂的 ZnO 薄膜由于与 ITO 相比低成本、无毒和对 H 等离子体的高耐久性而被广泛考虑。在这篇综述中，“共掺杂”是指 ZnO 薄膜中的阳离子 - 阳离子（两种等价或异价阳离子）和阳离子 - 阴离子（一种高价阳离子和一种低价阴离子）双掺杂。本文首先对 TCO、ITO 和单掺杂 ZnO 进行了概括描述，然后讨论了共掺杂 ZnO。我们系统地介绍了两种共掺杂研究的当前进展，并提供了批判性总结的结果，以获得概述，特别是关于电学特性。由于两种不同的阳离子同时取代锌位点的竞争性，阳离子-阳离子共掺杂导致宽范围的载流子浓度和电阻率值。由于较少的晶格缺陷，阳离子-阴离子共掺杂导致载流子浓度和电阻率值的预期变化，通常具有更高的迁移率。最后，文章最后简要讨论了在不久的将来要解决的问题和挑战。由于两种不同的阳离子同时取代锌位点的竞争性，阳离子-阳离子共掺杂导致宽范围的载流子浓度和电阻率值。由于较少的晶格缺陷，阳离子-阴离子共掺杂导致载流子浓度和电阻率值的预期变化，通常具有更高的迁移率。最后，文章最后简要讨论了在不久的将来要解决的问题和挑战。由于两种不同的阳离子同时取代锌位点的竞争性，阳离子-阳离子共掺杂导致宽范围的载流子浓度和电阻率值。由于较少的晶格缺陷，阳离子-阴离子共掺杂导致载流子浓度和电阻率值的预期变化，通常具有更高的迁移率。最后，文章最后简要讨论了在不久的将来要解决的问题和挑战。