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首页> 外文学位 >Defect-Induced Optoelectronic Response in Single-layer Group-VI Transition-Metal Dichalcogenides.
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Defect-Induced Optoelectronic Response in Single-layer Group-VI Transition-Metal Dichalcogenides.

机译：单层第VI族过渡金属硫族化物中的缺陷诱导光电响应。

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摘要

The ever-evolving symbiosis between mankind and nanoelectronics-driven technology pushes the limits of its constituent materials, largely due to the dominance of undesirable hetero-interfacial physiochemical behavior at the few-nanometer length scale, which dominates over bulk material characteristics. Driven by such instabilities, research into two-dimensional (2D) van der Waals-layered materials (e.g. graphene, transition metal dichalcogenides (TMDCs), boron nitride), which have characteristically inert surface chemistry, has virtually exploded over the past few years. The discovery of an indirect- to direct-gap conversion in semiconducting group-VI TMDCs (e.g. MoS2) upon thinning to a single atomic layer provided the critical link between metallic and insulating 2D materials. While proof-of-concept demonstrations of single-layer TMDC-based devices for visible-range photodetection, light-emission and solar energy conversion have showed promising results, the exciting qualities are downplayed by poorly-understood defectinduced photocarrier traps, limiting the best-achieved external quantum efficiencies to approximately ~1%.;This thesis explores the behavior of defects in atomically-thin TMDC layers in response to optical stimuli using a combination of steady-state photoluminescence, reflectance and Raman spectroscopy at room-temperature. By systematically varying the defect density using plasma-irradiation techniques, an unprecedented room-temperature defect-induced monolayer PL feature was discovered. High-resolution transmission electron microscopy correlated the defect-induced PL with plasma-generation of sulfur vacancy defects while reflectance measurements indicate defect-induced sub-bandgap light absorption. Excitation intensity-dependent PL measurements and exciton rate modeling further help elucidate the origin of the defect-induced PL response and highlights the role of non-radiative recombination on exciton conversion processes.;The results in this thesis shed light on the role of defects on atomically-thin TMDC optical behavior and point to yet-unexplored opportunities for further fundamental study and practical use of defects, which will expectedly benefit the development of scalable TMDC-based optoelectronic devices.
机译：人类与纳米电子驱动技术之间不断发展的共生关系推动了其构成材料的极限，这主要是由于在数纳米长的尺度上，不良的异质界面理化行为占支配地位，而这种杂化作用占主导地位的是散装材料的特性。在这种不稳定性的驱使下，过去几年来对具有特征惰性表面化学性质的二维（2D）范德华层材料（例如石墨烯，过渡金属二卤化金属（TMDC），氮化硼）的研究激增。半导体VI-族TMDC（例如MoS2）变薄到单个原子层后发现了间接到直接间隙转换，这在金属和绝缘2D材料之间提供了关键的联系。虽然基于单层TMDC的器件在可见光光电检测，发光和太阳能转换方面的概念验证演示显示出令人鼓舞的结果，但不良理解的缺陷引发的光载流子陷阱却淡化了令人兴奋的质量，从而限制了最佳的达到了约1％的外部量子效率。;本文结合稳态光致发光，反射率和拉曼光谱在室温下探索了原子薄TMDC层中的缺陷行为，这些行为是对光刺激的响应。通过使用等离子体辐照技术系统地改变缺陷密度，发现了前所未有的室温缺陷诱导的单层PL特征。高分辨率透射电子显微镜将缺陷诱导的PL与硫空位缺陷的等离子体生成相关联，而反射率测量表明缺陷诱导的亚带隙光吸收。激发强度相关的PL测量和激子速率模型进一步帮助阐明了缺陷诱导的PL反应的起源，并突出了非辐射复合在激子转化过程中的作用。原子上薄的TMDC光学行为，并为进一步的基础研究和缺陷的实际使用指出了尚未探索的机会，这有望使基于可扩展TMDC的光电器件的开发受益。

著录项

  • 作者

    Chow, Philippe K.;

  • 作者单位

    Rensselaer Polytechnic Institute.;

  • 授予单位 Rensselaer Polytechnic Institute.;
  • 学科 Materials science.;Nanoscience.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 104 p.
  • 总页数 104
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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