二硫化钼原子薄层半导体晶体中载流子弛豫动力学的飞秒瞬态吸收显微成像研究

项目名称： 二硫化钼原子薄层半导体晶体中载流子弛豫动力学的飞秒瞬态吸收显微成像研究

项目编号： No.61308069

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 无线电电子学、电信技术

项目作者： 时红艳

作者单位： 哈尔滨工业大学

项目金额： 25万元

中文摘要： 原子薄层二硫化钼半导体晶体作为具有直接带隙能带结构的类石墨烯材料，在纳米电子学和纳米光子学等领域具有非常广阔的应用前景。理解维度、厚度、基底及覆盖层局域环境等对激发态的性质以及不同弛豫过程的时间尺度的影响对于实现二维材料的实际应用极其重要，不同的弛豫过程及弛豫率最终影响器件的性能及效率。本项目提出利用超高时空分辨率的飞秒瞬态吸收成像技术研究原子薄层二硫化钼半导体晶体中的载流子弛豫动力学。利用泵浦-探测共扫描模式，分别用带隙能量之上及带隙能量之下的泵浦光进行激发，不同波长的探测光进行探测，实验和理论相结合研究量子受限效应，激子-声子耦合，以及基底、介电环境等对原子薄层二硫化钼材料的光学性质及载流子弛豫动力学过程的影响。通过该研究，揭示并控制二维原子薄层二硫化钼晶体中能量转移及载流子弛豫复合的动力学过程，为二硫化钼的器件化应用提供实验基础及理论依据。

中文关键词： 二硫化钼；飞秒瞬态吸收成像；载流子动力学；量子受限；介电环境

英文摘要： The novel atomically-thin 2D molybdenum disulfide(MoS2) semiconductor crystals with a direct band gap are highly promising for a wide range of applications including nanoelectronics, optoelectronics, and energy harvesting devices. Understanding the nature of the excited states and timescales for the different relaxation processes in relations to their reduced dimensionalities, thickness and local environment, such as substrates and deposited top layers, is important for realizing applications of these novel 2D materials. The radiative and nonradiative carries lifetimes determine photoluminescence quantum yields and ultimately the efficiency of optoelectronic devices. The main goal of this proposal is to provide a fundamental understanding of quantum confinement and environmental effects on carriers relaxation dynamics in atomically-thin 2D semiconducting crystals by ultrafast transient absorption microscopy with simultaneous temporal and spatial resolution by combining experimental and theoretical approaches. In this proposal, we will extend the transient absorption imaging approach both with above band gap and below band gap absorption to study carries dynamics in atomically thin MoS2, which provides insights into how quantum confinement effect, exciton-phonon coupling effect, thickness dependence effect, subst

英文关键词： Molybdenum Disulfide；Transient Absorption Microscopy；Carriers Dynamics；Quantum confinement Effects；Dielectric Environmental Effects