Tailoring the Functionality of ZnO via Highly Lattice Mismatched and Lattice Matched Alloying

通过高度晶格失配和晶格匹配合金化调整 ZnO 的功能

• 批准号: 1202532
• 负责人: Leah Bergman
• 金额: $ 43.29万
• 依托单位: Regents of the University of Idaho
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1202532&HistoricalAwards=false
• 关键词: Tailoring; Functionality; ZnO; via; Highly

NON-TECHNICAL DESCRIPTION: Zinc oxide (ZnO) is emerging as one of the materials of choice for ultraviolet (UV) applications, but only at a narrow energy range. ZnO is attractive because it is a very efficient light-emitter in a wide range of temperatures, and has a benign chemical nature. Creating an alloy is one route for tailoring optical properties and achieving additional light emissions at desired energies. Thus alloying ZnO with certain atomic constituents can add new optical and electronic functionalities to ZnO. The optical properties of the alloys depend on their material quality, and on how amenable to mixing, or soluble, are the atomic constituents in the ZnO matrix. This project focuses on the study of two ZnO-based alloy systems, Mg(x)Zn(1-x)O and ZnS(1-x)O(x), with the objective of achieving high-quality alloys with known solubility and material properties that enable optical properties by design at energy ranges above and below that of pure ZnO, respectively. In particular, the alloys may provide materials with tunable bandgaps and new optical emissions in the deep-UV as well as in the blue-green spectral ranges. This research has broader impact in the potential use of these alloys in the highly vital field of blue and UV semiconductor light sources and sensors, as well as in coating technologies for the protection of sensitive electronic devices operating in harsh environments. As part of this research effort, an educational outreach program is also being initiated that presents a series of lectures to the local community on the role of materials in consumer technology. The educational effort is coordinated with a professor from the Department of Philosophy at the University of Idaho, whose expertise is in enhancing communication in cross-disciplinary research and on the transfer of scientific and technical knowledge to the general public.TECHNICAL DETAILS: In this research, Mg(x)Zn(1-x)O with a high percentage of Mg composition that promotes the cubic phase is investigated with the goal of achieving bandgap engineered alloys in the UV range of 4 - 6 eV, while ZnS(1-x)O(x) is studied with the objective of creating materials with bandgap in the blue-green part of the visible spectrum. ZnS(1-x)O(x) is a highly-lattice mismatched alloy system, and may prove useful for enabling new electronic and optical properties, such as strong bandgap bowing into the visible spectrum, and modification of valence band to acceptor level separation for the case of doped samples. For this research, sintered ceramics, as well as films that are grown via a sputtering technique, are synthesized. Due to the different thermal equilibrium conditions of these two growth techniques, studying both types of materials is expected to yield comprehensive knowledge into key aspects of the alloys such as solubility limits, sample homogeneities, and metastabilities. The material properties are studied via several high-resolution atomic imaging techniques and X-ray diffraction, while the optical properties are studied via photoluminescence, Raman scattering, absorption, and infrared spectroscopy. Additionally, Hall effect measurements are employed for the investigation of doped ZnS(1-x)O(x) for understanding the valence - acceptor levels relation. The experimental studies are complemented with analytical modeling. The outcome of this research enables the creation of materials with a broad range of bandgaps and new emission lines in an important part of the spectrum. Another significant impact of this research is that for the advancement of ZnO as a viable material in quantum-well based devices, knowledge concerning its alloy systems is necessary, as the alloy constitutes the barrier component. The research is a collaborative effort between two PIs from the University of Idaho and from nearby Washington State University. A postdoctoral researcher, one graduate student, and an undergraduate student are supported by and participate in this research. As the PIs are strongly committed to educational efforts, several other undergraduates from diverse backgrounds take part in the research. The two laboratories provide an excellent opportunity for the students and the postdoctoral researcher to gain basic knowledge in optical materials as well as be trained in cutting-edge research techniques.

非技术描述：氧化锌 (ZnO) 正在成为紫外线 (UV) 应用的首选材料之一，但仅限于较窄的能量范围。 ZnO 很有吸引力，因为它在很宽的温度范围内都是一种非常高效的发光体，并且具有良好的化学性质。制造合金是调整光学特性并在所需能量下实现额外光发射的一种途径。因此，将 ZnO 与某些原子成分合金化可以为 ZnO 添加新的光学和电子功能。合金的光学特性取决于其材料质量，以及 ZnO 基体中原子成分的混合或溶解程度。该项目重点研究两种 ZnO 基合金体系 Mg(x)Zn(1-x)O 和 ZnS(1-x)O(x)，其目标是获得具有已知溶解度和材料特性的高质量合金，通过设计分别在高于和低于纯 ZnO 的能量范围内实现光学特性。特别是，这些合金可以提供具有可调谐带隙的材料以及在深紫外和蓝绿光谱范围内的新光学发射。 这项研究对于这些合金在蓝色和紫外半导体光源和传感器等高度重要领域的潜在用途，以及在保护在恶劣环境下运行的敏感电子设备的涂层技术方面具有更广泛的影响。 作为这项研究工作的一部分，还启动了一项教育推广计划，向当地社区举办一系列关于材料在消费技术中的作用的讲座。这项教育工作是与爱达荷大学哲学系的一位教授协调进行的，该教授的专长是加强跨学科研究的交流以及向公众传播科学和技术知识。技术细节：在这项研究中，研究了具有高比例 Mg 成分的 Mg(x)Zn(1-x)O，可促进立方相的形成，目标是在紫外光下实现带隙工程合金 范围为 4 - 6 eV，而研究 ZnS(1-x)O(x) 的目的是创建带隙位于可见光谱蓝绿部分的材料。 ZnS(1-x)O(x) 是一种高度晶格失配的合金系统，可能有助于实现新的电子和光学特性，例如强带隙弯曲到可见光谱，以及在掺杂样品的情况下修改价带以实现受主能级分离。 在这项研究中，合成了烧结陶瓷以及通过溅射技术生长的薄膜。 由于这两种生长技术的热平衡条件不同，研究这两种类型的材料有望获得有关合金关键方面的全面知识，例如溶解度限制、样品均匀性和亚稳定性。通过多种高分辨率原子成像技术和 X 射线衍射研究材料特性，通过光致发光、拉曼散射、吸收和红外光谱研究光学特性。 此外，霍尔效应测量用于研究掺杂 ZnS(1-x)O(x)，以了解价态 - 受体能级关系。实验研究通过分析模型得到补充。这项研究的成果使得能够创造出具有广泛带隙和在光谱的重要部分中具有新发射线的材料。这项研究的另一个重大影响是，为了推动 ZnO 作为量子阱器件中可行的材料，有关其合金系统的知识是必要的，因为该合金构成势垒成分。这项研究是爱达荷大学和附近华盛顿州立大学的两位 PI 之间的合作成果。一名博士后研究员、一名研究生和一名本科生受到并参与了这项研究。由于 PI 坚定地致力于教育工作，其他几位来自不同背景的本科生也参与了这项研究。这两个实验室为学生和博士后研究人员提供了获得光学材料基础知识和接受前沿研究技术培训的绝佳机会。