Optical links are being developed to transfer analogue tracking data and digital timing and control signals in the future Compact Muon Solenoid (CMS) experiment at CERN. The radiation environment inside the CMS tracker will be extreme, with hadron fluences up to -10i4/cm2 and ionising doses of -100kGy over the experimental lifetime. Prototype link elements, consisting of commercially available 13 lOnm multi-quantum-well InGaAsP lasers and InGaAs p-i-n photodiodes, have been irradiated in a fully packaged form with -6MeV neutrons to 10'5n/~m2, 24GeV protons to 4x10i4p/cm2 and '"Co-gammas to 100kGy. Three types of single-mode optical fiber, two pure-silica core and one Gedoped core, were irradiated in several stages with 6oCo-gammas to a total dose of -90kGy.Neutron and proton damage induced large increases in laser threshold and significant decreases in light output efficiency. P-i-n leakage current increased by up to 6-7 orders of magnitude for neutron and proton damage. P-i-n response was relatively unaffected until -2x 10'4n/cm2, or -4~1 0~~p / c m~, after which the photocurrent decreased rapidly. Gamma damage after lOOkGy was minor in comparison to hadron damage in both the lasers and p-i-n photodiodes. The radiation induced attenuation at 1300nm in the optical fibers was dependent upon the fiber type, with losses of O.OBdB/m for the pure-silica core fiber and 0.12dBIm in the Ge-doped core fiber, after -90kGy. The annealing in one of the pure-silica core fibers was found to be temporary in nature.

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The damage and strain induced by irradiation of both relaxed and pseudomorphic Ge,Si,-, films on Si(100) with 100 keV 28Si ions at room temperature have been studied by MeV 4He channeling spectrometry and x-ray double-crystal diffractometry. The ion energy was chosen to confine the major damage to the films. The results are compared with experiments for room temprature Si irradiation of Si( 100) and Ge( 100). The maximum relative damage created in low-Ge content films studied here (x=10%, 13%, 15%, 20%, and 22%) is considerably higher than the values obtained by interpolating between the results for relative damage in Si-irradiated single crystal Si and Ge. This, together with other facts, indicates that a relatively small fraction of Ge in Si has a significant stabilizing effect on the retained damage generated by room-temperature irradiation with Si ions. The damage induced by irradiation produces positive perpendicular strain in Ge,Si, --x, which superimposes on the intrinsic positive perpendicular strain of the pseudomorphic or partially relaxed films. In all of the cases studied here, the induced maximum perpendicular strain and the maximum relative damage initially increase slowly with the dose, but start to rise at an accelerated rate above a threshold value of -0.15% and 15%, respectively, until the samples are amorphized. The pre-existing pseudomorphic strain in the Ge,Sii-, film does not significantly influence the maximum relative damage created by Si ion irradiation for all doses and x values. The relationship between the induced maximum perpendicular strain and the maximum relative damage differs from that found in bulk Si( 100) and Ge( 100).

About 500-nm-thick films of Ge,-,,6Sic64 and Ge o.28Si0.72 grown epitaxially on (100)Si have been oxidized at 700 "C in wet ambient. A uniform Ge,Sit-,O, oxide layer forms with a smooth interface between it and the unoxidized Ge$i, _ X layer below. The composition and structure of that layer remains unchanged as monitored by backscattering spectrometry or cross-sectional transmission electronic microscopy. The oxide of both samples grows as square root of oxidation duration. The parabolic rate constant increases with the Ge content and is larger than that for wet oxidation of pure Si at the same temperature. The absence of a regime of linear growth at this relatively low temperature indicates a much enhanced linear rate constant.

We have synthesized nanocrystalline Ge in vitreous SiO2 by annealing amorphous Ge0.38Si0.62O2 in hydrogen at 700 °C. The germanium dioxide in Ge0.38Si0.62O2 is thermodynamically unstable in the presence of hydrogen and thus precipitates out as elemental Ge. Elemental Si is not needed in this reduction process. Cross-sectional transmission electron microscopy reveals that the nucleation process is homogeneous, leading to a uniform distribution of small Ge crystallites imbedded in the remaining vitreous SiO2.