Three-Wave Mixing Spectroscopy of Buried Solid Interfaces and Thin Film Structures

小行星9701657 拟议的工作旨在采用二阶非线性光学技术来研究埋固体界面。 非线性光学方法是特别有吸引力的，因为它具有大多数光学探针的长穿透深度特性，以及所有二阶光学过程的固有界面灵敏度特性。 该研究将大力应用我们的非线性工具，以科学有趣的固-固界面系统，包括hererofilm结构，如SiC/Si和SiC/SiO2，金属/GaAs，金属/ZnSe，ZnSe/GaAs，II-VI基四元薄膜InP，和III-N氮化物基薄膜结构的新类。 不严格地说，这些材料的高质量膜被要求用于下一代电光器件，例如蓝光发射器和光电探测器。 拟议的调查将包括一系列开放式极化和频率相关的调查。 极化的研究有可能确定与这些薄膜的生长，如混合相，和取向不良的总结构问题。 固体界面的频率相关的研究，以及在许多情况下的散装薄膜，将提供独特的光谱信息，这些系统的潜力，揭示新的信息，在这些系统中的缺陷，带分布和应变。 当异种晶体突然邻接时，形成具有与相邻块体材料的物理性质根本不同的物理性质的界面区域。 由于结的微观特性通常在决定材料的宏观特性方面起着突出的作用，因此了解结很重要。 在最基本的层面上，我们想了解特定的界面化学计量如何带来特定的界面能级结构，能带偏移，能带分布和形态。 在更高的技术水平上，“界面质量”已知会影响注入激光器和LED的特性，以及光电探测器和微电子电路中的电荷传输。 因此，一个具有重要基础和实际意义的问题是阐明各种界面性质，如能级结构在影响材料整体性质中所起的作用。 不幸的是，由于传统的光谱学缺乏界面特异性，并且传统的表面诊断具有有限的穿透深度，因此难以通过常规手段探测掩埋的固体界面。 拟议的工作旨在采用二阶非线性光学技术来研究这些接口。 非线性光学方法是特别有吸引力的，因为它具有大多数光学探针的长穿透深度特性，以及所有二阶光学过程的固有界面灵敏度特性。 ***

9701657 Yodh The proposed work seeks to employ second-order nonlinear optical techniques to study buried solid interfaces. The nonlinear optical method is particularly attractive because it possesses the long penetration depths characteristic of most optical probes, and the intrinsic interface sensitivity characteristic of all second-order optical processes. The research will vigorously apply our nonlinear tools to new classes of scientifically interesting solid-solid interface systems including hererofilm structures such as SiC/Si and SiC/SiO2, metal/GaAs,metal/ZnSe,ZnSe/GaAs, II-VI-based Quaternary thin films on InP,and III-N nitride-based thin film structures. Loosely speaking, high quality films of these materials are required for the next generation of electro-optic devices such as blue light emitters and photodetectros. The proposed investigations will encompass a range of open ended polarization and frequency-dependent investigations. The polarization studies have the potential to identify gross structural problems associated with the growth of these thin films such as mixed phases, and misorientation. The frequency-dependent studies of the solid interfaces, and in many cases of the bulk thin films as well, will provide unique spectroscopic information about these systems with the potential to reveal new information about defects, band profiles, and strain in these systems. %%% When dissimilar crystals are abruptly adjoined, an interfacial region is formed with physical properties that are fundamentally different from those of the neighboring bulk materials. Since the microscopic characteristics of the junction often play a prominent role in determining the macroscopic properties of the material, the junction is important to understand. At the most basic level we would like to understand how specific interfacial stoichiometries bring about particular interfacial energy level structures, band offsets, band profiles, and morphologies. On a mo re technological level, "interface quality" is known to affect the properties of injection lasers and LED's, as well as charge transport in photodetectors and microelectronic circuits. A roblem of great fundamental and practical importance then, is to elucidate the role played by various interfacial properties such as level structure in affecting the properties of the material as a whole. Unfortunately the buried solid interface is difficult to probe by conventional means because traditional optical spectroscopies lack interface specificity, and traditional surface diagnostics have a limited penetration depth. The proposed work seeks to employ second-order nonlinear optical techniques to study these interfaces. The nonlinear optical method is particularly attractive because it possesses the long penetration depths characteristic of most optical probes, and the intrinsic interface sensitivity characteristic of all second-order optical processes. ***