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

本研究主要研究四面体配位半导体中的振动、电子和磁激发。我们将研究用分子束外延和化学气相沉积方法制备的体相和亚微米异质结。II-VI和III-V半导体(体层、外延层和量子井结构)将使用拉曼光谱、布里渊光谱、调制反射率以及光致发光和吸收光谱进行研究。将磁性离子引入到II-VI化合物中，产生了一类新的材料，称为稀磁半导体，具有显着的磁光效应。将对这些系统进行进一步的探索，特别强调低维材料。还将研究有意引入到金刚石和碳化硅中的施主和受主的振动光谱和电子能级。该计划的主旨是提供对四面体配位半导体的物理性质的基本了解，这些半导体的光学特性构成了许多光电子应用的基础。四面体配位半导体家族包括众所周知的第IV族半导体，例如C、Si和Ge以及II-V族(例如，GaAs、InSb等)。以及II-VIS(例如，CdTe、ZnTe等)。这些材料中的电子、振动和磁激发将通过使用各种技术的光谱研究来检查。这种光谱研究的结果将产生与它们的光学性质有关的重要基本量，并有望形成许多光电子器件的基础。特别是，引入到II-VIS中的磁性离子产生了显著的磁光效应，这在磁隔离器和光学传感器方面具有潜在的应用前景。这些新颖的先进材料系统既可用于实验研究，也可用于理论研究，这要归功于在大规模和亚微米尺寸的新半导体生长过程中越来越多地采用了巧妙的技术。这项工作将与几个工业研究实验室的科学家和技术人员合作完成，他们将提供许多材料。此外，该项目还受益于与阿贡国家实验室的积极合作。

This research focuses on the vibrational, electronic, and magnetic excitations in tetrahedrally coordinated semiconductors. Both bulk and submicron heterostructures fabricated by molecular beam epitaxy and chemical vapor deposition will be investigated. II-VI and III-V semiconductors (bulk, epilayers, and quantum well structures) will be examined using Raman, Brillouin, modulated reflectivity, and photoluminescence and absorption spectroscopy. Magnetic ions introduced into II-VI compounds have resulted in a new class of materials called diluted magnetic semiconductors which possess striking magneto-optic effects. Further exploration of these systems will be undertaken with special emphasis on materials of low dimensionality. The vibrational spectra and electronic levels of donors and acceptors intentionally introduced into diamond and silicon carbide will also be studied. The thrust of the program is to provide a fundamental understanding of the physical properties of tetahedrally coordinated semiconductors whose optical characteristics form the basis of many optoelectronic applications. %%% The family of tetrahedrally coordinated semiconductors encompasses the well known group IV semiconductors such as C, Si, and Ge as well as the II-Vs (e.g., GaAs, InSb, etc.) and the II-VIs (e.g., CdTe, ZnTe, etc.) The electronic, vibrational, and magnetic excitations in these materials will be examined through spectroscopic investigations using a variety of techniques. The results of such spectral studies will yield important fundamental quantities related to their optical properties and are expected to form the basis of many optoelectronic devices. In particular, magnetic ions introduced into the II-VIs generate striking magneto- optic effects which have potential applications as magnetic isolators and optical sensors. These novel advanced material systems are accessible to both experimental and theoretical studies, thanks to the ingenious techniques increasingly exploited in the growth of new semiconductors in the bulk as well as with submicron dimensions. The work will be done in collaboration with scientists and technologists at several industrial research laboratories who will supply many of the materials. In addition, the program benefits from an active collaboration with the Argonne National Laboratory.