CAREER: Point Defects in Two-dimensional Material Systems: Fundamentals and New Perspectives

职业：二维材料系统中的点缺陷：基础知识和新视角

• 批准号: 1552220
• 负责人: Sefaattin Tongay
• 金额: $ 50万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1552220&HistoricalAwards=false
• 关键词: CAREER; Point; Defects; Two; dimensional

Nontechnical Description: It is known that introducing defects or imperfections into a crystalline material, either by removing atoms or adding foreign atoms, can change material's properties, and this approach has led to many ground breaking applications such as light emitting diodes, transistors and sensors. Today, there is a good understanding of how to manipulate these imperfections to achieve the desired properties of traditional semiconductors such as silicon. However, researchers are just starting to understand how to use defects to manipulate a whole new class of materials: two-dimensional (2D) semiconductors that are atomically thin, which have an unusual set of properties and are expected to perform far better than traditional semiconductors in some regards. The research component of this CAREER award is to explore innovative ways to introduce defects in 2D materials and to study how defects change the 2D material's properties. One way this can be done is to remove atoms by striking the material with energetic particles. Alternatively, foreign atoms with different electrical charges can be anchored in their place. The research team uses state-of-the-art techniques to visualize how these imperfections form, how they react and how they impact the material properties. This project also brings nanoscience and 2D material concepts to the public through open house events and summer camps for high-school students, as well as participation of graduate and undergraduate students in active research. Findings from this project are disseminated through journal publications, conference presentations, and a publicly-accessible 2D materials database, which the team is developing in collaboration with a non-profit organization, MaterialsProject.org.Technical Description: This research project aims to uncover the physics of point defects, in particular those in emerging 2D semiconducting materials such as WS2, GeSe, GaSe, and InTe. The research team uses advanced high-resolution spectroscopy and microscopy techniques to investigate chalcogen vacancies, anti-site defects, and substitutionals. Defects are introduced at desired defect concentrations during growth or after growth by alpha-particle irradiation to achieve desired material properties. Nano-photoluminescence, ultra-fast spectroscopy, and electron energy loss spectroscopy measurements allow determination of energy states of defects and effects of defects on the excitonic complexes, optical absorption and emission characteristics, as well as electronic structure of 2D materials. Transmission electron microscopy (TEM) studies help to determine structural characteristics, relaxation dynamics, and diffusion speed of defects. The overarching goal is to measure, analyze, and establish the roles of point defects in determining the optical and electronic properties of select 2D semiconducting materials and explore new routes to control material properties on demand.

非技术描述：众所周知，在晶体材料中引入缺陷或缺陷，无论是通过移除原子还是添加外来原子，都可以改变材料的性质，这种方法已经导致了许多开创性的应用，如发光二极管、晶体管和传感器。今天，人们很好地理解了如何操纵这些不完美的东西，以实现硅等传统半导体所希望的特性。然而，研究人员刚刚开始了解如何利用缺陷来操纵一种全新的材料类别：原子厚度很薄的二维(2D)半导体，这种半导体具有一系列不同寻常的特性，在某些方面预计会比传统半导体表现得更好。这个职业奖的研究部分是探索在2D材料中引入缺陷的创新方法，并研究缺陷如何改变2D材料的性能。一种可以做到这一点的方法是通过用高能粒子撞击材料来去除原子。或者，具有不同电荷的外来原子可以固定在它们的位置上。研究小组使用最先进的技术来可视化这些缺陷是如何形成的，它们是如何反应的，以及它们如何影响材料性能。该项目还通过面向高中生的开放参观活动和夏令营，以及研究生和本科生参与积极研究，将纳米科学和2D材料概念带给公众。该项目的研究成果通过期刊出版物、会议报告和公开可访问的2D材料数据库传播，该数据库是该团队与非营利性组织MaterialsProject.org合作开发的。技术描述：该研究项目旨在揭示点缺陷的物理，特别是在新兴的2D半导体材料中，如WS2、GeSE、GaE和Inte。研究小组使用先进的高分辨率光谱和显微技术来研究硫族空位、反位缺陷和取代基。通过α粒子辐照在生长过程中或生长后以期望的缺陷浓度引入缺陷，以获得所需的材料性能。纳米光致发光、超快光谱和电子能量损失谱测量可以确定缺陷的能态和缺陷对激子复合体的影响、光学吸收和发射特性以及二维材料的电子结构。透射电子显微镜的研究有助于确定缺陷的结构特征、松弛动力学和扩散速度。总体目标是测量、分析和确定点缺陷在决定选定的2D半导体材料的光学和电子性能中的作用，并探索根据需要控制材料性能的新途径。