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，而半导体纳米线的性质在很大程度上取决于在合成过程中调节其组成的能力。该项目旨在探索基于化学的过程来编码复杂的圆柱形硅线，并了解磷、硼和氮掺杂原子在硅纳米线生长过程中的掺入情况。研究了丝合成条件对这些掺杂原子的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估。此外，还考察了掺杂原子对纳米线的光学性质和形状的影响，目标是优化螺旋纳米线的生长和可控制地在纳米线内产生发光中心。该项目在化学、物理和工程之间架起桥梁的主题上培训本科生和研究生-提供在纳米材料合成、微制造、光电测量和建模方面的广泛经验。小学和当地图书馆的各种项目和示范、一年一度的公共科学博览会和针对高中生的暑期研究使科学概念得以广泛传播。技术描述：半导体纳米线通常由金属催化生长，采用气-液-固(VLS)和气-固-固(VSS)生长工艺。本项目旨在开发一种组合的VLS-VSS生长方法，以单纳米或亚纳米的空间分辨率对硅纳米线中的磷、硼和氮掺杂原子进行编码。掺杂剂的加入被用来调节纳米线的光学性质和形貌。例如，探索了共掺杂作为一种新的方法来制备手性导线，并研究了这些结构的手性光学响应。此外，氮的掺入被用来引入具有发光特性的缺陷态。硼和磷的调制被用来产生与p-n结光探测器集成的深亚波长光子晶体腔，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，可以用来在纳米线中编码光子和光电子功能。

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.