CAREER: Developing Advanced Morphological Control of Nanowires to Encode Photonic and Optoelectronic Functionality

非技术描述：半导体纳米线因其潜在的电子和光子应用而被广泛探索，其性能在很大程度上取决于在合成过程中调制其成分的能力。本项目旨在探索基于化学的过程来编码复杂的圆柱形硅线，并了解在硅纳米线生长过程中磷、硼和氮掺杂原子的掺入。研究了金属丝合成条件对掺杂原子浓度和空间分布的影响，并对原子突变界面的可能性进行了评价。此外，还研究了掺杂原子对纳米线光学性质和形状的影响，以优化螺旋纳米线的生长和在线内可控地产生发光中心。该项目培养本科生和研究生的主题，在化学，物理和工程之间架起桥梁-提供纳米材料合成，微加工，光电测量和建模方面的广泛经验。在小学和地方图书馆举办的各种项目和演示、每年的公共科学展览和高中生的暑期研究使科学概念得到广泛传播。技术描述：半导体纳米线通常是通过金属催化生长，使用气-液-固（VLS）和气-固-固（VSS）生长过程合成的。本项目旨在开发一种VLS-VSS复合生长方法，在单纳米或亚纳米空间分辨率的硅纳米线中编码磷、硼和氮掺杂原子。掺杂剂的掺入可以调制纳米线的光学性质和形貌。例如，共掺杂作为一种创建手性线的新方法被探索，并研究了这些结构的手光学响应。此外，氮的掺入引入了具有发光特性的缺陷态。硼和磷的调制被用来创建深亚波长光子晶体腔集成的p-n结光电探测器，表现出波长选择性检测。这些努力扩展了一套自下而上的合成方法，可用于编码纳米线中的光子和光电子功能。

Nontechnical Description: Semiconductor nanowires have been widely explored for their potential electronic and photonic applications, and the properties of the wires are largely dictated by the ability to modulate their composition during synthesis. This project aims to explore chemistry-based processes to encode complex cylindrical silicon wires and to understand the incorporation of phosphorus, boron, and nitrogen dopant atoms in silicon nanowires during their growth. The effect of wire synthesis conditions on the concentration and spatial profiles of these dopant atoms is studied, and the potential for atomically-abrupt interfaces is evaluated. In addition, the influence of the dopant atoms on the optical properties and shape of the wires is examined, targeting optimized growth of spiraling nanowires and controllable creation of luminescent centers within the wires. The project trains undergraduate and graduate students in topics that bridge the interface between chemistry, physics, and engineering - providing breadth of experience in nanomaterials synthesis, microfabrication, optoelectronic measurements, and modeling. Various programs and demonstrations in elementary schools and local libraries, annual public science expositions and summer research for high-school students enable broad dissemination of the scientific concepts. Technical Description: Semiconductor nanowires are often synthesized by metal-catalyzed growth using vapor-liquid-solid (VLS) and vapor-solid-solid (VSS) growth processes. This project aims to develop a combined VLS-VSS growth method to encode phosphorus, boron, and nitrogen dopant atoms in silicon nanowires with single or sub-nanometer spatial resolution. The incorporation of dopants is used to modulate the optical properties and morphology of the nanowires. For instance, co-doping is explored as a novel method to create chiral wires, and the chiro-optical response of these structures is studied. In addition, the incorporation of nitrogen is used to introduce defect states with luminescent characteristics. Modulation of boron and phosphorus is employed to create deep-subwavelength photonic crystal cavities integrated with p-n junction photodetectors that exhibit wavelength-selective detection. These efforts expand the set of bottom-up synthetic methods that can be used to encode photonic and optoelectronic functionality in nanowires.