Session APS2: APS II - Condensed Matter and Nanomaterials
3:30 PM–5:42 PM, Friday, March 23, 2007
Foster Science Building Room: 458
Chair: Tikhon Bykov, McMurry University
Abstract ID: BAPS.2007.TSS07.APS2.5
Abstract: APS2.00005 : Muonium in Silicon Germanium Alloys
4:18 PM–4:30 PM
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Abstract 
Authors:
Brent Carroll
(Texas Tech University)
Roger Lichti
(Texas Tech University)
Philip King
(ISIS Facility, Rutherford Appleton Laboratory)
Gurkan Celebi
(Istanbul University)
We report observations of muonium defect centers in bulk, single crystalline Silicon Germanium alloys. Analysis of both bond-centered and interstitial T-site muonium gives a test for predictions of isolated hydrogen defect levels in Si$_{1-x}$Ge$_{x}$ alloys across the full alloy composition range. Temperature dependent amplitudes for neutral Mu$_{BC}$ and Mu$_{T}$ from high transverse field muon spin rotation (HTF-$\mu $SR) measurements yield ionization energies for these muonium centers. The hyperfine parameter for Mu$_{BC}$ varies linearly with alloy composition, whereas for Mu$_{T}$ it varies non-linearly, perhaps due to faster motion among germanium T-sites compared to silicon. Our HTF-$\mu $SR analysis of Si$_{0.16}$Ge$_{0.84}$ shows that the diamagnetic muonium species grows around 130 K with an activation energy of 102(1) meV. Similar data for Si$_{0.10}$Ge$_{0.90}$ give an activation energy of 67(3) meV. Both HTF-$\mu $SR and RF resonance results show two distinct Mu$_{T}$ signals for x $\ge $ 0.84. These states are tentatively assigned to T-sites with all Ge neighbors versus those with a Si neighbor.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2007.TSS07.APS2.5