EAGER: Understanding Photochemical 2H-1T Phase Transition in Monolayer MoS2

非技术描述：超薄过渡金属二硫属化合物（TMD）材料在柔性、低功耗、透明的电子和光电子领域具有广阔的应用前景。操纵原子排列，称为晶相，可以将TMD从半导体材料转变为金属材料，这是改善整体器件性能和/或获得新功能的有前途的方法。目前的相位工程方法要么依赖于昂贵和有害的化学品，要么与大规模制造不相容。该项目旨在开发一种新型的光化学方法，该方法可控，可扩展，低成本，环境友好，与电子器件制造兼容，以诱导二硫化钼的相变。该研究推进了TMD材料相变机制的知识状态，并探索了TMD材料在可穿戴电子产品，可折叠显示器和照明以及先进的集成医疗设备中的应用潜力。研究工作与教育和外展活动相结合，包括培训学生使用TMD材料，组织夏季科学夏令营，以及为传统上在STEM领域代表性不足的高中生提供研究实习计划。技术描述：该项目提出了一种新的光化学概念，用于单层二硫化钼的相变，以解决2D性能改进的迫切需要。基于TMD的电子/光电器件。这个EAGER项目的目标是了解单层二硫化钼中光化学诱导的2 H到1 T相变，并建立加工结构和结构性能的相关性。为了实现这一目标，本项目的目标是：（1）通过光化学形成的异质相二硫化钼的系统表征来验证相变机制，并通过改变工艺参数来评估相变的可控性;（2）研究亚稳金属相的稳定机制，以提高器件的可靠性;以及（3）评估相工程二硫化钼的有趣的光学和电学性质。本研究采用先进的结构表征、光学分析、器件制造和电学测量相结合的方法，对相变机制和相位工程2D-TMD材料有了基本的了解。

Non-technical Description: Ultra-thin transition metal dichalcogenides (TMDs) materials are promising candidates for flexible, low-power and transparent electronics and optoelectronics. Manipulating the atomic arrangements, referred to as crystal phases, can transform TMDs from semiconducting to metallic materials, which is a promising way to improve the overall device performance and/or to attain new functionalities. The current phase-engineering methods either rely on expensive and hostile chemicals or are incompatible with large-scale manufacturing. This project aims to develop a novel photochemical approach, which is controllable, scalable, low-cost, environmentally benign and compatible with electronic device fabrication, to induce phase-change in molybdenum disulfide. The research advances the state of knowledge of the phase-change mechanisms in TMD materials and explores the potential of TMD materials for applications in wearable electronics, foldable displays and lightings, and advanced integrated medical devices. The research effort is integrated with education and outreach activities, including training students in TMD materials, organizing a summer science camp and research internship programs for high school students that are traditionally underrepresented in the STEM field.Technical Description: This project proposes a novel photochemical concept for phase transition in monolayer molybdenum disulfide to address the pressing need for performance improvement in 2D-TMD based electronic/optoelectronic devices. The goal of this EAGER project is to understand photochemically induced 2H to 1T phase transformation in monolayer molybdenum disulfide and to establish processing-structure and structure-property correlations. In pursuit of this goal, the project objectives are to (1) validate the phase change mechanism through systematic characterizations of photo-chemically formed hetero-phase molybdenum disulfide and evaluate the controllability of the transition by varying processing parameters; (2) investigate the stabilization mechanism of the metastable metallic phase for improved device reliability; and (3) evaluate intriguing optical and electrical properties of phase-engineered molybdenum disulfide. Combined approaches of advanced structural characterization, optical analysis, device fabrication and electrical measurements are used in this research to gain fundamental understandings of the phase-change mechanism and the phase-engineered 2D-TMD materials.