CAREER: Continuous-flow microplasma synthesis of Group IV semiconductor nanoparticles

在半导体工业中，等离子体表面工艺，如反应离子蚀刻和薄膜的化学气相沉积，对集成电路的制造至关重要。在一定的操作条件下，在气相中形成的小颗粒被观察到称为尘埃等离子体。虽然等离子体合成纳米颗粒对纳米技术的应用很有吸引力，但在这些“批处理”中。过程中，很难控制颗粒的成核和生长，以获得纳米级颗粒的窄分散。此外，通常与这些过程相关的低操作压力（10托）和大型基础设施使其难以扩展到商业应用。本研究的重点是合成窄分散，表面功能化的第四族半导体纳米颗粒，包括硅和金刚石。第四族半导体由于其优异的电学和化学性能以及与微电子加工的兼容性而成为重要的材料。然而，由于合成方面的挑战，对这些材料纳米级性质的基本理解仍然未知。本文提出了一种基于连续流动常压微等离子体的合成方法。微等离子体是小型化的直流电（dc）辉光放电，其特点是高浓度的高能电子（1-10 eV）在高压下稳定等离子体。由于微等离子体定义的小体积（小于1nl），颗粒生长受到限制，允许生产纳米尺寸的非团聚颗粒。通过气溶胶粒径分级监测在常压下连续产生的纳米颗粒，实时获取粒径分布。此外，将收集颗粒并通过高分辨率透射电子显微镜（HRTEM），微拉曼光谱和光致发光（PL）进行表征。精确调谐的硅和金刚石纳米颗粒的可用性将导致对这些材料中的电子约束的基本理解。更广泛的影响：这项研究与教育活动紧密结合，包括为K-12学校的年轻女性建立一个新项目。该计划由两个部分组成：1)通过新的研究性选修课程，让初高中学生接触到包括纳米技术在内的当前技术领域的研究；2)为高中学生提供在大学进行独立研究的机会。这些外展活动旨在通过让学生接触科学和工程实践，加强他们在数学和科学方面的教育。

CBET-0746821, SankaranIn the semiconductor industry, plasma-based surface processes such as reactive ion etching and chemical vapor deposition of thin films are vitally important to the manufacturing of integrated circuits. Under certain operating conditions, the formation of small particles in the gas phase has been observed known as a dusty plasma. While plasma synthesis of nanoparticles is attractive for nanotechnological applications, in these ?batch? processes, it is difficult to control particle nucleation and growth in order to obtain narrow dispersions of nanometer-sized particles. In addition, the low operating pressures (10 Torr) and large infrastructure normally associated with these processes makes it difficult to scale-up for commercial applications.This research focuses on the synthesis of narrowly dispersed, surface-functionalized Group IV semiconductor nanoparticles including silicon and diamond. The Group IV semiconductors are important materials because of their excellent electrical and chemical properties and compatibility with microelectronics processing. However, fundamental understanding of nanoscale properties in these materials remains unknown because of synthetic challenges. Here, a synthesis methodology is proposed based on a continuous-flow, atmospheric-pressure microplasma. Microplasmas are miniaturized versions of direct-current (dc) glow discharges characterized by large concentrations of energetic electrons (1-10 eV) which stabilize the plasma at high pressures. Because of the small volume defined by the microplasma (less than 1 nL), particle growth is restricted, allowing the production of nanometer-sized, non-agglomerated particles. Continuous production of nanoparticles at atmospheric pressure will be monitored by aerosol size classification to obtain particle size distributions in real time. In addition, the particles will be collected and characterized by high-resolution transmission electron microscopy (HRTEM), micro-Raman spectroscopy, and photoluminescence (PL). The availability of precisely tuned silicon and diamond nanoparticles will lead to a fundamental understanding of electronic confinement in these materials.Broader impacts: The research is closely integrated with educational activities that include the establishment of a new program for young women in K-12 schools. The program is comprised of two components: 1) expose middle school and high school students to research in current technological areas including nanotechnology through a new research-based elective class and 2) provide high school students an opportunity to conduct independent research at the university. The outreach activities are expected to enhance the education of students in math and science by exposing them to the practice of science and engineering.