XANES Studies of Zinc Tin Oxide Films Deposited by Atomic Layer Deposition: Revealing Process-Structure Relationships for Amorphous Oxide Semiconductors
XANES Studies of Zinc Tin Oxide Films Deposited by Atomic Layer Deposition: Revealing Process-Structure Relationships for Amorphous Oxide Semiconductors
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DOI：
10.1021/acs.jpcc.2c05656
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发表时间：
2022-12
期刊：
影响因子：
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通讯作者：
O. Trejo;Tae H. Cho;Sami Sainio;N. Dasgupta
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文献类型：
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作者：
O. Trejo;Tae H. Cho;Sami Sainio;N. Dasgupta
非晶氧化物半导体在显示器、信息技术、能源和催化方面的技术相关性已经增长。最近的研究工作集中在需要开发这些材料的电子结构的设计原则。在这里，我们系统地改变阳离子组成和退火温度的锌锡氧化物薄膜使用原子层沉积（ALD）和研究它们的过程结构的关系与同步辐射X射线吸收近边光谱（XANES）。测量的O K-边，Sn M-边，和Zn L-边进行了分析与从头算和非线性统计建模，以了解薄膜的几何和电子结构的变化。这种方法的一个关键发现是能够测量Zn和Sn s轨道对导带最小值附近态密度的相对贡献的变化。此外，我们确定和描述了在使用非晶氧化物半导体（AOS）材料系统时的关键工艺结构设计原则：（1）使用互补衍射和吸收光谱技术来表征沉积的配位环境;（2）考虑配位环境中的渐变和突变作为工艺参数（化学计量、退火等）的函数; (3)揭示和利用相关的知识和相互依存的协调环境，轨道杂化，态密度和能带结构。在未来，这种多模态X射线分析和建模框架可以应用于了解优化器件AOS性能所需的工艺-结构关系。
Amorphous oxide semiconductors have grown in technological relevance in displays, information technology, energy, and catalysis. Recent research efforts have converged on the need to develop design principles for the electronic structure of these materials. Here, we systematically vary the cation composition and annealing temperatures of zinc tin oxide films using atomic layer deposition (ALD) and study their process-structure relationships with synchrotron X-ray absorption near-edge spectroscopy (XANES). Measurements of the O K-edge, Sn M-edge, and Zn L-edge are analyzed withab initioand nonlinear statistical modeling to understand the changes in geometric and electronic structure of the films. A key finding from this approach is the ability to measure the changes in the relative contribution of the Zn and Sn s orbitals to the density of states near the conduction band minimum. Furthermore, we identify and delineate critical process-structure design principles when working with amorphous oxide semiconductor (AOS) material systems: (1) use of complementary diffraction and absorption spectroscopy techniques to characterize the as-deposited coordination environment; (2) accounting for gradual and abrupt changes in coordination environment as a function of processing parameters (stoichiometry, annealing, etc.); (3) revealing and exploiting the relevant knowledge and interdependence of coordination environments, orbital hybridizations, the density of states, and band structures. In the future, this multimodal X-ray analysis and modeling framework can be applied to understand the process-structure relationships needed to optimize AOS performance in devices.