Growth of Ultra Thin Metal Alloy Films

0854345 Ekerdt本研究计划研究在非晶衬底上生长超薄（小于9 nm）非晶金属薄膜。将研究化学生长方法，包括化学气相沉积和等离子体增强化学气相沉积。在第一性原理计算的指导下，本研究将研究合金元素，如磷，硼，硅和锡对稳定钌，钴，镍和钯薄膜中的非晶微观结构的作用。目标是在最小合金浓度下形成非晶结构，从而保留金属特性。研究将集中在化学和物理方法，以增加成核密度或改变膜组装过程，以实现2-4 nm厚的连续膜。将作出改变，以增加基板的缺陷密度和实验也将探索选择性的表面钝化剂，以阻止对生长的金属反应，并迫使在基板上的额外的成核。研究目标是了解使反应和过程，这将导致尽可能薄的连续薄膜，并与非晶特性的超薄薄膜。工作计划将涉及薄膜生长和表征研究，并将涉及表面研究，以阐明前体如何与衬底相互作用，因为配体和衬底被修改。该研究利用德克萨斯大学的专业知识和实验基础设施来生长和表征薄膜，并研究表面反应。键合和反应在基板表面和薄膜界面将进行探讨。薄膜成分和化学键合将使用X射线光电子能谱，二次离子质谱和低能离子散射光谱。一整套表征设备将用于研究薄膜，包括椭圆偏振光谱仪、原子力显微镜、X射线散射光谱仪和高分辨率电子显微镜。金属膜在传感器、光学和微电子学中有应用，并且随着应用和系统的关键尺寸或大小的减小，金属膜的厚度也必须最多减少到几十个原子直径，并且必须具有特定的微结构。该计划旨在描述薄膜是如何形成的，重点是成核和岛状聚结，将薄膜结合到衬底上的界面层的演变，散装材料的性质如何随厚度而变化，以及当膜厚度接近5- 10 μ m的厚度时，短程有序是如何精确地保持的。Veronoi多面体特征尺寸的15倍。拟议研究的更广泛影响这项研究的动机一般是在非晶衬底上的超薄金属膜在应用中的核心作用例如电极、传感器、光学器件、热阻挡层和扩散阻挡层。该计划旨在探索短程有序在超薄非晶金属的形成和稳定中的作用和性质。此外，该计划的地址，并试图描述的界面和表面反应，影响膜的演变，因为它从成核岛转化为一个合并，连续的膜。非晶和多晶薄膜的成核和生长问题是共同的。这项研究将直接支持研究生的培养，并间接为本科生提供参与开放式研究项目的机会。PI和研究生将开发一个展览，这将有助于解释激励这项研究，传感器和微电子技术的革命性和当前的设备，并向公众和预科学生介绍这些概念。他们将通过德克萨斯大学赞助的各种场所展示它，如一年一度的UT开放日和德克萨斯纪念博物馆。

0854345EkerdtThis research program investigates the growth of ultra thin (less than 9 nm) amorphous metal films on amorphous substrates. Chemical growth methods will be studied that include chemical vapor deposition and plasma-enhanced chemical vapor deposition. Guided by first-principles calculations, this research will examine the role of alloying elements, such as phosphorus, boron, silicon and tin on stabilizing an amorphous microstructure in ruthenium, cobalt, nickel and palladium films. The goal is to force an amorphous structure at the minimum alloy concentration so that the metal properties are retained. The research will focus on chemical and physical methods to increase the nucleation density or to alter the course of film assembly to realize continuous films that are 2-4 nm thick. Changes will be made to increase the defect density of the substrates and experiments will also explore selective surface passivants to block reaction on the growing metal and force additional nucleation on the substrate. The research objectives are an understanding of the enabling reactions and processes that will lead to the thinnest possible continuous film, and to an ultra thin film with amorphous character. The program of work will involve film growth and characterization studies and it will involve surface studies to elucidate how the precursors interact with the substrates as the ligands and substrates are modified. The research leverages the expertise and experimental infrastructure at the University of Texas to grow and characterize films and to study surface reactions. Bonding and reactions at the substrate surface and at the film interface will be explored. Film composition and chemical bonding will be followed using X-ray photoelectron spectroscopy, secondary ion mass spectrometry and low energy ion scattering spectroscopy. A full complement of characterization facilities will be used to study the films, including spectral ellipsometry, atomic force microscopy, X-ray scattering spectroscopy, and high resolution electron microscopy.Intellectual Merit: Metal films find applications in sensors, optics and microelectronics, and as the critical dimensions or size of the applications and systems decrease, the metal films thickness also must decrease to tens of atomic diameters at most and must have a specific microstructure. This program seeks to describe how films form, with an emphasis on nucleation and island coalescence, the evolution of interfacial layers that bind the film to the substrate, how properties of bulk materials scale with thickness, and precisely how short range order is preserved as the film thickness approaches thicknesses that are 5- 15 times the characteristic dimension of the Veronoi polyhedra.Broader Impacts of the Proposed Research This research is motivated in general by the central role ultra thin metal films on amorphous substrates have in applications such as electrodes, sensors, optics, thermal barriers, and diffusion barriers. This program seeks to explore the role and nature of short-range-order in the formation and stabilization of ultra thin amorphous metals. Further this program addresses and seeks to describe the interfacial and surface reactions that affect the evolution of the films as it transforms from nucleated islands to a coalesced, continuous film. Issues of nucleation and growth are common to both amorphous and polycrystalline films.The research will directly support the training of graduate students and indirectly provide opportunities for undergraduates to participate in open-ended research projects. The PI and the graduate student will develop an exhibit that will help explain the revolutionary and current devices that motivate this research, sensors and microelectronics, and introduce these concepts to the general public and to precollege students. They will present it and display it through a variety of University of Texas sponsored venues, such as the annual UT Open House and the Texas Memorial Museum.