9623611 Estle 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. ***
