Synthetic control of electron-phonon coupling in semiconductor quantum dots

半导体量子点电子声子耦合的综合控制

• 批准号: 1506803
• 负责人: Anne Kelley
• 金额: $ 52万
• 依托单位: University of California - Merced
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1506803&HistoricalAwards=false
• 关键词: Synthetic; control; electron; phonon; coupling

With this award, the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program is funding Professors Anne Myers Kelley and David Kelley at the University of California at Merced to apply laser-based spectroscopic techniques and computational modeling to study mechanisms whereby light energy is converted to heat in quantum dots (QDs) which are small semiconductor structures containing hundreds to thousands of atoms. The quantitative understanding that will be gained regarding these processes will enable the controlled chemical synthesis of QDs that are optimized for several types of technological applications. These include efficient solar energy capture and conversion, low power dissipation artificial lighting, and laser-based biological imaging for medical diagnostics. UC Merced is a Hispanic Serving Institution and more than half of its undergraduates are first-generation college students, and this research will actively involve both graduate and undergraduate students from traditionally underrepresented groups.This project aims to accurately measure and quantitatively understand the factors that determine the extent of electron-phonon coupling (EPC) in nanometer sized semiconductor quantum dots (QDs) and to synthetically control the extent of EPC. Preliminary calculations suggest that by judicious choice of materials and morphology it is possible to greatly increase or decrease the magnitude of EPC in core-shell and core-alloy-shell structures compared to single component QDs. Both well-known and novel structures based on II-VI semiconductors are synthesized and characterized and their EPC measured through quantitative resonance Raman spectroscopy, including analysis of absolute excitation profiles, overtone intensities, and depolarization ratios,. This study tests the hypothesis that EPC for optical phonons in polar crystals is determined largely by the amount of charge separation produced by electron-hole pair formation via the Fröhlich mechanism, and that it can be varied by controlling the valence and conduction band energies such that the electron and hole wavefunctions have different amounts of overlap. The novelty of this approach is to not only measure EPC accurately for specific materials but also engineer structures that permit the control of EPC.

有了这个奖项，加利福尼亚大学的大分子，超分子和纳米化学（MSN）计划正在为教授Anne Myers Kelley和Anne Myers Kelley和David Kelley提供资金，以将基于激光的光谱技术和计算技术和计算模型应用于研究机制，从而将光能转换为千分之一的量子（QDS）。在这些过程中将获得的定量理解将使QD的受控化学合成能够针对几种类型的技术应用进行优化。其中包括有效的太阳能捕获和转换，低功率耗散人工照明以及用于医学诊断的基于激光的生物成像。 UC Merced is a Hispanic Serving Institution and more than half of its undergraduates are first-generation college students, and this research will actively involve both graduate and undergraduate students from traditionally underrepresented groups.This project aims to accurately measure and quantitatively understand the factors that determine the extent of electron-phonon coupling (EPC) in nanometer sized semiconductor quantum dots (QDs) and to合成控制EPC的程度。初步计算表明，与单个成分QD相比，通过明智地选择材料和形态的材料和形态，可以大大增加或减少Core-shell和Core-Alloy-Shell结构中EPC的幅度。基于II-VI半导体的知名和新结构都是合成和表征的，它们的EPC通过定量谐振拉曼光谱法测量，包括分析绝对兴奋的曲线，夸张的强度和沉积比。这项研究检验了以下假设：极性晶体中的光音子的EPC在很大程度上取决于通过Fröhlich机制由电子孔对形成产生的电荷分离量，并且可以通过控制价和传导带的能量来改变它，从而使电子波和孔波有不同的重叠量。这种方法的新颖性不仅要准确地测量特定材料的EPC，而且还要测量允许控制EPC的工程结构。