Raman, Brillouin, Infrared and Modulation Spectroscopy of Collective and Localized Excitations in Tetrahedrally Coordinated Semiconductors and Their Heterostructures

本项目致力于用各种光学技术研究四面体配位半导体及其异质结构中的集体激发和局域激发。这项研究将集中在由轻原子(金刚石、碳化硅、氮化硼和丁二烯)组成的同位素控制半导体中的集体和局域激发。将关注同位素控制的钻石、硅、碳化硅多型体以及II-VI和III-V化合物半导体中施主束缚电子和受主束缚空穴的电子状态。此外，还将探索和描绘由II-VI和III-V半导体谱系派生的黄铜矿中等电子杂质和补偿杂质的局域振动和能隙模式。我们将研究分子束外延制备的纳米结构的降维约束下的集体激发。将采用拉曼光谱、布里渊光谱、红外光谱、光致发光和调制反射/透射率光谱技术，并辅以压电谱和磁光谱学来解决上述问题。学生将参与这项研究。他们将接受当前半导体物理学前沿领域之一的培训，从而为进入21世纪的科学/技术劳动力做好准备。这项研究涉及几种实验光学技术在先进半导体材料提出的问题中的应用。这些材料在目前的技术中发挥了很大的作用，但对它们的行为仍然缺乏基本的了解。这项研究将为超硬材料的合成和使用提供有用的信息，如金刚石、碳化硅、氮化硼和其他已被用作超硬薄膜涂层的材料。这些材料的行为可以通过有意地、有控制地引入特定杂质或通过操纵它们的同位素组成来改变。这些改变的行为有望改善材料在高温/高功率电子器件应用中的性能。这个项目为学生提供了许多参与的机会。该项目的参与者将接触到这一领域的兴奋和智力挑战，该领域在当代基础科学中非常重要，对潜在的应用具有重要意义。这样发展出来的专业知识将为他们将来在学术界和政府以及高科技光电子行业的研究和开发事业做好准备。

This project is devoted to the investigation of collective and localized excitations in tetrahedrally coordinated semiconductors and their heterostructures by means of a variety of optical techniques. The research will focus on the collective and localized excitations in isotopically controlled semiconductors composed composed of light atoms (diamond, SiC, BN and BP). Attention will be given to electronic states of donor-bound electrons and acceptor-bound holes in isotopically controlled diamond, Si, silicon carbide polytypes, as well as II-VI and III-V compound semiconductors. In addition, localized vibrations and gap modes of isoelectronic and compensated impurities will be explored and delineated in the chalcopyrites genealogically derived from the II-VI and III-V semiconductors. Collective excitations subjected to the constraints of the reduced dimensionality of nanostructures fabricated with molecular beam epitaxy will be investigated. Raman, Brillouin, Infrared , photoluminescence and modulated reflectivity/transmission spectroscopic techniques supplemented by piezo- and magneto-spectroscopy will be employed to address the above problems. Students will participate in this research. They will receive training in one of the forefront areas of current semiconductors physics and will thereby be prepared to enter the scientific/technical workforce of the 21st Century. This research deals with the application of several experimental optical techniques to problems posed by advanced semiconductor materials. These materials play a great role in current technology but a basic understanding of their behaviors is still lacking. This research will provide information that will be useful for the synthesis and use of ultrahard materials, such as diamond, silicon carbide, boron nitride and others that have found applications as superhard thin film coatings. The behavior of these materials can be changed by the deliberate, controlled introduction of specific impurities or by manipulating their isotopic composition. The changed behaviors hold the promise of improved performance of the materials in applications of high temperature/high power electronic devices. This project offers many opportunities for the participation by students. Participants in the program will be exposed to the excitement and intellectual challenges of an area that is important in contemporary basic science and significant for potential applications. The expertise thus developed will prepare them for a future in academia and government as well as a career in research and development in the high tech optoelectronic industry.