NER: Synthesis of Nanoscale Structures of New Direct Bandgap Semiconductors

我们计划对在紫外可见光谱和红外光谱范围内具有直接可调带隙的新型半导体的自组装纳米结构的制备进行探索性研究，主要工作将集中在XCZN家族中一个全新的半导体系统的纳米尺度结构的生长上，其中X是IV族元素(Si，Ge，Sn)，Z是III族金属(Al，Ga，In)。具体地说，这些结构是四元宽带隙材料(GEC)1-x(GaN)x的量子点和柱子，带隙在1.6到3.3 eV之间可调。这些材料通过合适的缓冲层直接在硅上产生，利用气-液-固(VLS)机制，提供了微调纳米结构尺寸和空间分布的灵活性。这项工作的一个重要目标是将(GEC)1-x(GaN)x和相关的光学合金与硅技术相结合，使它们的全部潜力能够实现为商业上可行的材料。该研究计划还包括在Si-Ge-Sn系中合成具有可调电子和结构特性的红外纳米结构。这些材料包括Ge1-XSNX量子点以及直接在硅衬底上创建的相关(SiGe)1-XSNX和(Si4Ge)1-XSNX纳米结构。这种情况下的新奇之处在于这些硅基系统的直接带隙性质。通过椭圆偏振光谱、拉曼探针、光致发光、阴极发光、透射式红外光谱和电子能量损失谱对其电子结构和光学性质进行了深入的研究。包括高分辨电子显微镜、离子通道(RBS)、高分辨X射线衍射、低能电子显微镜(LEEM)和原子力显微镜在内的结构表征被广泛用于提供关于纳米结构的结构和形态的质量的快速反馈，从而最终导致更好的合成路径的设计。拟议活动的更广泛的影响是使化学、物理和材料科学的本科生受益，通过让他们参与到创造新的有用的半导体材料的新型纳米结构的研究和发现过程中。这些学生，包括代表性不足的团体的成员，也将接触到当地微电子和光电子实验室的工业环境，以获得第一手知识，并深入了解半导体和纳米科学研究的技术创新。

We propose to conduct exploratory research on the fabrication of self-assembled nanometer-scale structures of new classes of semiconductors with direct tunable bandgaps in the UV/visible and infrared spectral regions.A major part of the work will focus on the growth of nanoscale sized structures of a completely new semiconductor system in the XCZN family where X is a group IV element (Si, Ge, Sn) and Z is a group III metal (Al, Ga, In). Specifically, these structures are quantum dots and pillars of the quaternary wideband gap material (GeC) 1-x (GaN) x with an adjustable bandgap between 1.6 and 3.3 eV. These materials are created directly on Si via suitable buffer layers utilizing the vapor-liquid-solid (VLS) mechanism, which provides flexibility of fine-tuning the size and spatial distributions of the nanostructures. An important objective of this work is to integrate (GeC) 1-x(GaN)x and related optical alloys with Si technologies so that their full potential can be realized as commercially viable materials.The research program also covers the synthesis of infrared nanostructures in the Si-Ge-Sn system with tunable electronic and structural properties. These materials include Ge1-xSnx quantum dots as well as related (SiGe) 1-xSnx and (Si4Ge) 1-xSnx nanostructures created directly on silicon substrates. The novelty in this case is the direct-bandgap nature of these Si-based systems. The electronic structure and optical properties will be thoroughly studied by spectroscopic ellipsometry, Raman microprobe, photoluminescence, cathodoluminescence, transmission IR spectroscopy and electron energy loss spectroscopy. Structural characterization involving high resolution electron microscopy, ion channeling (RBS), high resolution x-ray diffraction, low energy electron microscopy (LEEM) and atomic force microscopy are used extensively to provide rapid feedback about the quality of the structure and morphology of the nanostructures, thus ultimately leading to better design of the synthetic pathways.The broader impact of the proposed activity is to benefit undergraduates in chemistry, physics and materials science, by involving them in the research and discovery process of creating novel nanostructures of new and useful semiconductor materials. These students, including members of underrepresented groups, will also be exposed to the industrial environment at local microelectronic and optoelectronic laboratories in order to gain first-hand knowledge and an in-depth appreciation of the technical innovations in semiconductor and nanoscience research