Growth and Properties of III-VI Heterostructures

该项目的重点是异质外延生长的III-VI基半导体和相关的结构，电子和光学性质的这类材料。该研究旨在阐明III-VI薄膜生长的机制，并将III-VI生长技术和材料表征发展到这些材料可用于光电应用的阶段。基于III-VI材料的界面化合物将用于控制III-VI和更标准的电子材料的异质外延，包括它们用于促进层状和岛状纳米结构的形成。与体III-VI族材料相关的问题，差的机械和热性能，正在通过在诸如Si、GaAs和CaF 2的衬底上使用薄膜来解决。新一代材料的开发需要关于控制其电子，光学和结构特性的相互作用约束的新的基础知识。本项目致力于通过研究普通电子材料和III-VI基材料之间的异质界面形成来阐明这些限制的作用。主要目标是：建立基于纳米异质外延生长工艺的实验和理论框架，以优化III-VI异质结构的结构、电子和光学特性;利用III-VI界面化合物控制半导体纳米结构的形成;评估III-VI异质结构的结构、电子和光学特性，以实现新型光电应用的可行性。该方法集中在两个领域：（i）GaxSey、AlxSey及其合金在Si（111）、Si（100）、GaAs（100）和CaF 2（111）上的成核、生长和性质，以及（ii）将所得薄膜用作a）GaAs和ZnSe的层状和岛状生长以及B）GaxSey -AlxSey超晶格的衬底。生长动力学，形态和量子点特性将研究与纳米级分辨率使用原位扫描探针显微镜，超高压转移光电子能谱和近边缘X射线吸收，和非原位高分辨率透射电子显微镜和能量损失谱。将使用光电子能谱和衍射、电子衍射、离子散射能谱和光谱（光热、反射-透射、光致发光和拉曼散射）探测面积平均性质。该项目涉及材料科学专题领域的基础研究问题，具有很高的潜在技术相关性。该研究将为电子/光子器件的新方面提供基础材料科学知识。从研究中获得的基本知识和理解，预计将有助于提高先进器件和电路的性能和稳定性，为设计和生产改进的材料和材料组合提供基本的理解和基础。 该计划的一个重要特点是通过在一个基本和技术上重要的领域对学生进行培训来整合研究和教育。

This project focuses on heteroepitaxial growth of III-VI based semiconductors and on interrelated structural, electronic, and optical properties of this class of materials. The research seeks to elucidate mechanisms of III-VI thin film growth, and to develop III-VI growth technology and materials characterization to the stage where these materials may be utilized for optoelectronic applications. Interface compounds based on III-VI materials will be used to control heteroepitaxy of both III-VI and more standard electronic materials, including their use to promote both laminar and islanded nanostructure formation. Problems associated with bulk III-VI materials, poor mechanical and thermal properties, are being addressed through use of thin films on substrates such as Si, GaAs and CaF2 . Development of this new generation of materials requires new, basic knowledge about the interacting constraints that control their electronic, optical and structural properties. This project strives to elucidate the role of these constraints through studies of heterointerface formation between common electronic materials and III-VI based materials. Primary goals are: to establish an experimental and theoretical framework based on nanoscale heteroepitaxial growth processes to optimize structural, electronic and optical properties of III-VI heterostructures; to exploit III-VI interface compounds to control semiconductor nanostructure formation; to evaluate structural, electronic, and optical properties of III-VI-based heterostructures for feasibility in novel optoelectronic applications. The approach is to concentrate in two areas: (i ) nucleation, growth and properties of GaxSey, AlxSey , and their alloys on Si(111), Si(100), GaAs(100), and CaF2 (111), and (ii) use of the resultant thin films as substrates for a) laminar and islanded growth of GaAs and ZnSe and b) GaxSey - Alx Sey superlattices. Growth kinetics, morphologies and quantum dot properties will be studied with nanoscale resolution using in situ scanning probe microscopy, UHV-transfer photoelectron spectroscopy and near-edge x-ray absorption, and ex situ high resolution transmission electron microscopy and energy loss spectroscopy. Area-averaged properties will be probed using photoelectron spectroscopy and diffraction, electron diffraction, ion scattering spectroscopy, and optical spectroscopies (photothermal, reflection-transmission, photoluminescence, and Raman scattering).%%%The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of electronic/photonic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***