Element-specific local structure of crystalline and amorphous CuI-based alloys

碘化铜（CuI）显然是实现新型全透明电子器件所需的高性能透明p型半导体的最有前途的材料之一。用第三种元素掺杂或合金化CuI提供了根据特定应用的需要定制电学和光学性质的潜力。所得三元化合物可以是结晶或无定形性质的。在这两种情况下，局部原子排列会显著影响重要的材料特性，从而影响器件性能。因此，本计画的目的是利用X射线吸收光谱法来研究CuI基三元合金的元素特定的局部结构。在第一个资助期内，我们已经分析了Cu-Sn-I-O和CuBrxI 1-x薄膜和粉末，揭示了材料中不同元素的配位，并确定了特定元素的局部结构参数，如配位数，键长和键长变化（无序）。在第二个资助期内，我们将把这些研究扩展到研究单位研究的新型三元合金，包括通过等价或异价阳离子取代实现的结晶合金（分别为AgxCu 1-Xi、RbxCu 1-Xi或CuI：Se、CuI：Ni）和通过掺入适当的异价元素（如In或Mo）稳定的非晶合金。用X射线吸收光谱确定的元素特定的局部结构为生长过程的优化提供了重要的反馈，特别是对于标准衍射技术不再适用的非晶合金。此外，局部结构参数可以作为理论计算的基准，它们将有助于解释和理解电学和光学测量的结果。通过这种方式，我们的研究有助于全面了解生长条件，结构和重要材料特性之间的相关性，这是推进CuI基材料在未来透明电子器件中实际应用的先决条件。

Copper iodide (CuI) is clearly one of the most promising materials for realizing a high-performance transparent p-type semiconductor required for novel fully transparent electronic devices. Doping or alloying CuI with a third element offers the potential to tailor the electrical and optical properties according to the needs of a specific application. The resulting ternary compounds can be of crystalline or amorphous nature. In both cases, the local atomic arrangements significantly affect important material properties and hence the device performance. Therefore, it is the aim of this project to study the element-specific local structure of CuI-based ternary alloys using X-ray absorption spectroscopy. In the first funding period, we have already analysed Cu-Sn-I-O and CuBrxI1-x thin films and powders, revealing the coordination of the different elements in the material and determining the element-specific local structural parameters such as coordination numbers, bond lengths and bond length variations (disorder). In the second funding period, we will extend these studies to novel ternary alloys investigated by the Research Unit, including crystalline alloys realized by either isovalent or aliovalent cation substitution (AgxCu1-xI, RbxCu1-xI or CuI:Se, CuI:Ni, respectively) and amorphous alloys stabilized by incorporation of suitable aliovalent elements such as In or Mo. The element-specific local structure determined with X-ray absorption spectroscopy provides important feedback for the optimization of the growth procedures, especially for amorphous alloys, where standard diffraction techniques are no longer adequate. Furthermore, the local structural parameters can serve as benchmark for theoretical calculations and they will help to interpret and understand the results from electrical and optical measurements. In this way, our study strongly contributes to a comprehensive understanding of the correlations between growth conditions, structure and important material properties, which is a prerequisite to advance CuI-based materials on their way to practical application in future transparent electronic devices.