Epitaxial Ge/Si(100) Quantum Dots and Mn-Based Ferromagnetic Group IV Semiconductors

本计画旨在探讨异质磊晶锗/矽（100）量子点之微影模板组装相关的基本材料问题。理想的系综由周期性排列的，相同的，连贯的（无缺陷）锗岛。将采用电子束光刻图案化衬底的外延过生长来周期性地定位点。这种技术有望比其他方法更有利于异质外延量子点的有序化。光刻模板在应变层SiGe过生长期间被平坦化，从而有效地将图案化衬底处的形貌周期性转化为平面生长前沿处的弹性周期性。量子点在平面衬底上的弹性能量最小值处的放置允许它们容易地集成到功能架构中。此外，任何蚀刻引起的损伤在过度生长期间被掩埋。点间距和周期性可以通过图案间距的变化而变化，从而为生产周期性单点或多点阵列提供灵活性。应变SiGe层过生长过程中的平坦化依赖于表面形貌、成分和失配应变之间的相互作用。该项目将采用原子力显微镜来表征表面形貌，并采用最先进的高空间分辨率电子显微镜来表征成分，以实现更好的理解。一类新的Mn基铁磁IV族半导体，晶格匹配的Si：Mn和应变SiGe：Mn，也将在Si（100）上生长，以评估它们在Si基材料中的“自旋电子学”应用中的效用。这些磁性半导体将被集成到异质结构，包括异质外延Ge量子点，以便可以评估自旋极化载流子的注入效率。%该项目解决了与具有技术相关性的电子/光子材料相关的基础研究问题，并强调研究与教育的整合。该项目将涉及来自代表性不足群体的研究生和本科生。一名女研究生的论文研究将得到支持，一名西班牙裔研究生将参与由ASU/国家实验室奖学金支持的密切相关的项目。本科生将得到REU补充和ASU物理REU网站奖的支持。PI将参与扩大其范围和影响的活动，包括参与亚利桑那州立大学纳米科学与技术研究生课程的开发。这将是一个跨学科的计划，跨越文理学院和工程与应用科学学院。*

This project aims to investigate fundamental materials issues related to lithographically templating ensembles of heteroepitaxial Ge/Si(100)quantum dots. Ideal ensembles consist of periodically arranged, identical, coherent (defect free) Ge islands. Epitaxial overgrowth of electron beam lithography patterned substrates will be employed to periodically position the dots. This technique is expected to have advantages over other methods for ordering heteroepitaxial quantum dots. The lithographic template is planarized during strained-layer SiGe overgrowth, effectively translating topographic periodicity at the patterned substrate into elastic periodicity at the planar growth front. Quantum dot placement at elastic energy minima on a planar substrate allows them to be easily integrated into functional architectures. Additionally, any etch-induced damage is buried during overgrowth. Dot spacing and periodicity may be varied through changes in the pat-tern pitch, providing flexibility for producing periodic single or multi-dot arrays. Planarization during strained SiGe layer overgrowth relies on the interplay between surface morphology, com-position and misfit strains. The project will employ atomic force microscopy to characterize sur-face topography and state-of-the-art high spatial resolution electron microscopy to characterize composition to achieve greater understanding. A new class of Mn-based, ferromagnetic, group IV semiconductors, lattice-matched Si:Mn and strained SiGe:Mn, will also be grown on Si(100) in order to assess their utility for 'spintronics' applications in Si-based materials. These magnetic semiconductors will be integrated into heterostructures incorporating heteroepitaxial Ge quantum dots so that the efficiency for injection of spin-polarized carriers may be assessed. %%% The project addresses fundamental research issues associated with electronic/photonic materials having technological relevance and emphasizes the integration of research and education. The project will involve graduate students from underrepresented groups and undergraduate students. The dissertation research of a female graduate student will be supported and a Hispanic graduate student will be involved in a closely related project supported by an ASU/National Labs fellowship. Undergraduate students will be supported by REU supplements and the ASU Physics REU site award. The PI will be involved in activities which broaden its scope and impact, including participation in development of a Nanoscience and Technology graduate program at ASU. This will be an interdisciplinary program spanning the Colleges of Liberal Arts and Sciences and En-gineering and Applied Sciences.***