Collaborative Research: Muonium Dynamics in Semiconductors

这个项目是对半导体中介子原子缺陷中心的动态性质的研究。当植入的正介子捕获电子时，就会形成介子，并模仿难以直接研究的分离氢杂质的行为。硅中介子元素的数据揭示了三种电荷态和两种结构构型，以及这些态之间的许多跃迁。推广了Si中介子跃迁动力学和态稳定性的模型，并获得了Ge， GaAs和其他III-V材料的参数。μ子自旋共振和平交共振谱提供了状态识别并给出了结构细节，而磁场和温度对退极化率的依赖则提供了扩散和跃迁动力学的信息。相似氢中心非常相似的动态性质对浅掺杂氢钝化效率及其对半导体材料器件相关电学和光学性质的影响至关重要。这项研究利用了氢和μ子（一种由一个电子和一个正μ子组成的原子，一种不稳定的粒子）之间的相似性，以获得有关氢在半导体中的行为的信息，这些信息无法从直接研究中获得。在硅或砷化镓等半导体中常见的杂质中，氢具有最不寻常的性质。氢不是形成使半导体电子成为可能的供体或受体，而是移动到现有的供体或受体并中和它们。因此，氢可以非常显著地影响器件的特性。氢杂质的直接研究有严重的局限性；然而，muonium研究提供了类似的信息，并且对那些最难直接解决的问题提供了最丰富的信息。目前的项目扩展了成功的介子研究，以获得对含氢装置中活跃过程的理解。* * *

9623823 Lichti This project is an investigation of the dynamic properties of muonium defect centers in semiconductors. Muonium is formed when an implanted positive muon captures an electron, and mimics the behavior of isolated hydrogen impurities which are difficult to study directly. Data on muonium in Si has revealed three charge states and two structural configurations, along with numerous transitions among these states. A model of the muonium transition dynamics and state stabilities in Si is being generalized, and parameters obtained for Ge, GaAs, and other III-V materials. Muon spin resonance and level-crossing resonance spectra provide state identifications and give structural details, while the magnetic-field and temperature dependences of depolarization rates yield information on diffusion and transition dynamics. Very similar dynamic properties of the analogous hydrogen centers are crucial to the efficiency of hydrogen passivation of shallow dopants and its effect on the device- related electrical and optical properties of a semiconductor material. %%% This research exploits the similarities between hydrogen and muonium (an atom consisting of an electron bound to a positive muon, an unstable particle) in order to obtain information about the behavior of hydrogen in semiconductors which cannot be obtained from direct studies. Of all of the common impurities in semiconductors such as silicon or gallium arsenide, hydrogen has the most unusual properties. Rather than forming the donors or acceptors which make semiconductor-based electronics possible, hydrogen moves to existing donors or acceptors and neutralizes them. Consequently hydrogen can very substantially influence device characteristics. Direct investigation of hydrogen impurities has severe limitations; however, muonium studies supply similar information and have been most informative about those questions which are hardest to attack directly. The current project extends successful muonium studies to obtain an understanding of processes active in devices containing hydrogen. ***