Controlling and quantifying two-level systems, disorder and ideality in vapor deposited amorphous thin films

控制和量化气相沉积非晶薄膜中的两级系统、无序性和理想性

• 批准号: 1809498
• 负责人: Frances Hellman
• 金额: $ 48.09万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-15 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1809498&HistoricalAwards=false
• 关键词: Controlling; quantifying; two; level; systems

Non-Technical SummaryAmorphous materials lack structural order, making them difficult to describe and making it difficult to calculate and predict their properties compared to crystalline materials which consist of spatially repeated atoms. This lack of understanding, however, does not prevent the important applications possible or the scientific impact of amorphous materials; plastics, silicate glasses, and amorphous silicon photovoltaics are examples that are pertinent to daily life, industry, and technologies. Amorphous superconductors are a remarkable example of how a fundamental scientific property transcends structural imperfection. The properties of an amorphous material depend strongly on how it was produced, and there are some well-defined known defects, but it is not clear how to describe the different amorphous structures produced by different methods, even for a single element material, nor what the nature of a defect is in a fully disordered material. Disorder exists on different length and energy scales, ranging from local, atomic-sized disorder to larger scales. Intriguingly, there exists the notion of an "ideal glass", which while remaining thoroughly disordered, lacks imperfections in that disorder and thus approaches the uniqueness of a crystal, including reproducibility and predictability of its properties. The project will look at two types of materials, one a classic semiconductor alloy and the other a strongly bonded oxide, and determine the relationship between types of disorder and defects produced by different preparation methods and for different atoms, and the tunability of the "ideality" of disordered materials. The work will create an enhanced understanding of what causes mechanical and dielectric losses in technologically important amorphous materials and how to control these. More broadly, it will yield improved understanding and control of amorphous materials of technological and fundamental scientific significance. The project will also educate and train students and help to increase diversity participation in science; the PI and her research group actively engage in efforts to make physics accessible to underrepresented STEM ethnic and socioeconomic minorities. Technical SummaryIn more detail, this project will look at understanding order within a completely disordered (amorphous) material, and will provide insight into how vapor deposition enables creation of ultrastable glasses with low density of tunneling states (TLS), and for which materials this process works. Recent experiments show that two extremely different vapor deposited materials (indomethacin and silicon) form ultrastable glasses with enthalpy near the corresponding crystal and with a low density of tunneling states, strongly suggestive that these are close to ideal glasses. The proposed work will use two classes of amorphous materials to test the hypothesis that ultrastability is achieved by vapor deposition only when growth is done near the Kauzmann temperature TK, at which the ideal glass is theoretically produced, and only if there is sufficient surface atomic mobility. If true, this would open the door to the creation of other near-ideal low loss glasses and give insight on the nature of the elusive ideal glass state in different materials. The hypothesis that ideal glasses inherently have strongly suppressed TLS will also be tested. The many proposed characterization studies will give insights about defects, TLS, and stability of amorphous materials, and will hopefully point toward generalizable structural features that herald the presence or absence of TLS. The proposed materials directly impact many aspects of technology including dielectrics for tunnel barriers, phase change memories (a-Ge and related alloys), ultra-fast time-of-flight radiation detection (a-Se), and flash memories, catalysis, quantum computing, and high-k dielectrics in transistors and superconducting qubits (a-Al2O3).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

与由空间重复的原子组成的结晶材料相比，非技术总结材料缺乏结构秩序，因此很难描述和难以计算和预测其性质。然而，缺乏理解并不能阻止重要的应用可能或无定形材料的科学影响；塑料，硅酸盐眼镜和无定形硅光伏是与日常生活，工业和技术有关的例子。无定形的超导体是一个重要的例子，说明了基本科学特性如何超越结构不完美。 无定形材料的特性在很大程度上取决于它的产生方式，并且存在一些明确的已知缺陷，但是尚不清楚如何描述由不同方法产生的不同的无定形结构，即使是单个元素材料，也不清楚缺陷的性质是完全无序的材料。疾病的长度和能量尺度的存在，范围从局部，原子大小的疾病到较大的尺度。有趣的是，存在着“理想玻璃”的概念，尽管该玻璃仍然完全无序，但在该疾病中缺乏缺陷，因此接近了晶体的独特性，包括其性质的可重复性和可预测性。该项目将研究两种类型的材料，一种是经典的半导体合金，另一种是牢固粘合的氧化物，并确定疾病类型与不同制剂产生的缺陷和不同原子产生的缺陷之间的关系，以及“理想性的可调性” “无序材料。 这项工作将增强对在技术上重要的无定形材料以及如何控制这些材料中导致机械和介电损失的原因。更广泛地说，它将改善对技术和基本科学意义的无定形材料的理解和控制。该项目还将对学生进行教育和培训，并帮助增加对科学的多样性参与； PI和她的研究小组积极进行努力，以使物理学可用于代表性不足的STEM种族和社会经济少数群体。技术摘要更多详细信息，该项目将考虑了解完全无序（无定形）材料中的秩序，并将提供有关如何使蒸气沉积如何能够创建具有低密度隧道状态（TLS）的超稳定眼镜的见解，以及在哪种材料中，此过程此过程此过程作品。最近的实验表明，两种截然不同的蒸气沉积材料（吲哚美辛和硅）形成了超高的玻璃，并在相应的晶体附近，隧道状态密度低，强烈暗示它们接近理想的玻璃。拟议的工作将使用两类的无定形材料来检验以下假设：仅当在Kauzmann温度TK附近生长时，通过蒸气沉积才能实现超强性，理论上是理想的玻璃，并且只有在足够的表面原子迁移率时才能实现。 。 如果是真的，这将为创建其他近乎理想的低损失眼镜的创建打开大门，并深入了解不同材料中难以捉摸的理想玻璃状态的性质。理想眼镜本质上强烈抑制的TLS的假设也将被测试。许多提出的表征研究将为无定形材料的缺陷，TL和稳定性提供见解，并希望指出可概括TLS存在或不存在的可概括结构特征。 提出的材料直接影响技术的许多方面，包括用于隧道屏障的介电，相变的记忆（A-GE和相关合金），超快速飞行时间辐射检测（A-SE）和闪光记忆，催化，量子晶体管和超导Qubits中的计算和高K电介质（A-AL2O3）。该奖项反映了NSF的法定任务，并且使用基金会的智力优点和更广泛的影响审查标准，被视为值得通过评估来获得支持。

项目成果

Structural tunability and origin of two-level systems in amorphous silicon

非晶硅中两能级系统的结构可调性和起源

• DOI: 10.1103/physrevmaterials.6.045604
• 发表时间: 2022
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: Jacks, H. C.;Molina-Ruiz, M.;Weber, M. H.;Maldonis, J. J.;Voyles, P. M.;Abernathy, M. R.;Metcalf, T. H.;Liu, X.;Hellman, F.
• 通讯作者: Hellman, F.

Two-level systems and growth-induced metastability in hydrogenated amorphous silicon

氢化非晶硅中的两能级系统和生长诱导的亚稳态

• DOI: 10.1088/2053-1591/abb498
• 发表时间: 2020
• 期刊: Materials Research Express
• 影响因子: 2.3
• 作者: Molina-Ruiz, M.;Jacks, H. C.;Queen, D. R.;Wang, Q.;Crandall, R. S.;Hellman, F.
• 通讯作者: Hellman, F.

Temperature effects on the structure and mechanical properties of vapor deposited a-SiO2

温度对气相沉积a-SiO2结构和力学性能的影响

• DOI: 10.1016/j.jnoncrysol.2022.121588
• 发表时间: 2022
• 期刊: Journal of Non-Crystalline Solids
• 影响因子: 3.5
• 作者: Jambur, V.;Molina-Ruiz, M.;Dauer, T.;Horton-Bailey, D.;Vallery, R.;Gidley, D.;Metcalf, T.H.;Liu, X.;Hellman, F.;Szlufarska, I.
• 通讯作者: Szlufarska, I.

Origin of mechanical and dielectric losses from two-level systems in amorphous silicon

非晶硅两能级系统机械和介电损耗的起源

• DOI: 10.1103/physrevmaterials.5.035601
• 发表时间: 2021
• 期刊: Physical Review Materials
• 影响因子: 3.4
• 作者: Molina-Ruiz, M.;Rosen, Y. J.;Jacks, H. C.;Abernathy, M. R.;Metcalf, T. H.;Liu, X.;DuBois, J. L.;Hellman, F.
• 通讯作者: Hellman, F.

Decoupling between propagating acoustic waves and two-level systems in hydrogenated amorphous silicon

氢化非晶硅中传播声波与两能级系统之间的解耦

• DOI: 10.1103/physrevb.104.024204
• 发表时间: 2021
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Molina-Ruiz, M.;Jacks, H. C.;Queen, D. R.;Metcalf, T. H.;Liu, X.;Hellman, F.
• 通讯作者: Hellman, F.