CAREER: Time-Dependent Density-Functional Approach for Ultrafast Nonlinear Excitations in Semiconductors

职业：半导体中超快非线性激励的瞬态密度泛函方法

• 批准号: 0448763
• 负责人: Carsten Ullrich
• 金额: $ 40万
• 依托单位: Missouri University of Science and Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-08-15 至 2005-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0448763&HistoricalAwards=false
• 关键词: CAREER; Time; Dependent; Density; Functional

TECHNICAL EXPLANATION:This CAREER award supports theoretical research on ultrafast nonequilibrium carrier dynamics in photoexcited bulk semiconductors and semiconductor heterostructures. The education component focuses on developing an innovative course for teaching condensed matter physics to undergraduate students. The PI plans to reformulate the semiconductor Bloch equations within time-dependent density functional theory to study nonequilibrium carrier dynamics in photoexcited bulk semiconductors and semiconductor heterostructures on femtosecond to picosecond time scales. Time dependent density functional theory offers a computationally tractable formalism for describing dynamical correlation effects. The PI aims to evolve a more realistic theoretical picture by developing a formal framework that includes non-parabolic bands beyond the effective mass approximation, a treatment of exchange and correlation accounting for memory and retardation effects, and a microscopic description of disorder scattering of "hot" electron distributions. The PI will investigate whether a spatially long-ranged exchange-correlation potential together with the reformulated semiconductor Block equations can capture ultrafast excitonic dynamics. Previous work using long ranged exchange-correlation potentials did not enter the nonlinear ultrafast regime to be explored by this work. The PI ultimately aims to apply this formal framework to the coherent control of nonlinear intersubband effects such as optical bistability, harmonic generation, terahertz pulse shaping, and populating selected excited subbands.In the education component, the PI will focus on education in condensed matter physics. The PI plans to develop an upper undergraduate level condensed matter physics course including: (1) a course content that emphasizes topics at the forefront of modern science and technology, (2) interactive hands-on computer simulations, (3) student group projects that involve developing simulation programs. A public web site will also be created to make newly developed simulation routines available under the GNU General Public License. NON-TECHNICAL EXPLANATION:This CAREER award supports theoretical research on quantum mechanical states of electrons in semiconductors that result from illumination by light. Recent advances in laser technology have opened a frontier where the quantum mechanical states of electrons are prepared and probed by very short pulses of laser light. The PI will develop a theoretical technique to describe how electrons in semiconductors respond to very short pulses of laser light. The technique holds promise for a description that at once includes important materials specific information and is accessible to current computer technology. The PI plans to apply the technique to investigate the detailed dynamics of the electrons and how to prepare and control quantum mechanical states. This work is fundamental research and also contributes to the intellectual foundations of future technologies. In the education component, the PI will focus on education in condensed matter physics. The PI plans to develop an upper undergraduate level condensed matter physics course including: (1) a course content that emphasizes topics at the forefront of modern science and technology, (2) interactive hands-on computer simulations, (3) student group projects that involve developing simulation programs. A public web site will also be created to make newly developed simulation routines available under the GNU General Public License.

技术说明：该职业奖支持光激发体半导体和半导体异质结构中超快非平衡载流子动力学的理论研究。教育部分的重点是开发一个创新的课程教学凝聚态物理本科生。PI计划在含时密度泛函理论中重新制定半导体布洛赫方程，以研究飞秒到皮秒时间尺度上光激发体半导体和半导体异质结构中的非平衡载流子动力学。含时密度泛函理论为描述动力学关联效应提供了一种易于计算的形式。PI的目的是通过开发一个正式的框架，其中包括非抛物带超出有效质量近似，治疗的交换和相关性占记忆和阻滞效应，以及微观描述的无序散射的“热”电子分布，发展一个更现实的理论图片。PI将研究空间长程交换相关势与重新制定的半导体Block方程是否可以捕获超快激子动力学。以前的工作，使用长程交换关联势没有进入非线性超快制度进行探索的这项工作。PI的最终目标是将这种形式化的框架应用于非线性子带间效应的相干控制，如光学双稳态、谐波产生、太赫兹脉冲整形和填充选定的激发子带。在教育部分，PI将专注于凝聚态物理学的教育。PI计划开发一个高本科水平的凝聚态物理课程，包括：（1）强调现代科学和技术前沿主题的课程内容，（2）交互式动手计算机模拟，（3）涉及开发模拟程序的学生小组项目。 还将建立一个公共网站，使新开发的模拟程序在GNU通用公共许可证下可用。非技术性解释：该职业奖支持对半导体中电子的量子力学状态进行理论研究，这些电子是由光照射引起的。激光技术的最新进展开辟了一个前沿领域，其中电子的量子力学状态是通过非常短的激光脉冲来制备和探测的。PI将开发一种理论技术来描述半导体中的电子如何响应非常短的激光脉冲。该技术有望提供一种描述，可以立即包括重要的材料特定信息，并可以通过当前的计算机技术进行访问。PI计划应用该技术来研究电子的详细动力学以及如何制备和控制量子力学状态。这项工作是基础研究，也有助于未来技术的知识基础。在教育部分，PI将侧重于凝聚态物理学教育。PI计划开发一个高本科水平的凝聚态物理课程，包括：（1）强调现代科学和技术前沿主题的课程内容，（2）交互式动手计算机模拟，（3）涉及开发模拟程序的学生小组项目。 还将建立一个公共网站，使新开发的模拟程序在GNU通用公共许可证下可用。