We investigate a cavity ring down setup that offers the possibility to measure the spectrally resolved reflectivities of high reflectivity mirrors. The setup consists of a resonator (ring down cavity) and an intensified CCD camera system combined with a spectrograph for spectral resolution. A commercial supercontinuum laser (350-1750 nm) is applied as a compact excitation source. It is based on a photonic crystal fiber that is pumped by a q-switched microchip laser (1.6 ns pulse duration, 25 kHz repetition rate). This combination allows simultaneously recording the transmittance of the cavity over a wide wavelength range determined by the excitation source and the spectral sensitivity of the detector. The photon lifetimes inside the cavity (ring down times) are measured with high spectral resolution by means of an intensified camera system. Subsequently shifting the "gate" of the image intensifier from short to long delay times after the excitation pulse allows calculation of the reflectivity spectrum of the mirrors. Comparison of these results with measurements using a conventional setup (laser diode 675 nm and photomultiplier tube) clearly shows the high potential of the method due to the multichannel excitation and the detection scheme.

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The annealing behavior of (111) Si implanted with cobalt to doses between 2.5X lOI and 2 X 10" cme2 at energies between 30 and 250 keV has been investigated. The silicide formation during postannealing has been found to proceed in two phases characterized by activation energies of 0.810.3 and 2.9*0.3 eV. During the first phase a fast Co redistribution and pronounced nucleation and growth of the CoSi, precipitates at defects has been observed. The investigation of the dose dependence proved that the amount of Co redistributed during this phase depends on the initial Co and defect concentration. However, the processes contributing to this fast Co redistribution require further investigation. The second step is well characterized by Ostwald ripening. Multiple implantations of Co at different energies have been applied to modify the Co concentration profile. In this way, it is possible to form Si/CoSi#/CoSi,-layer systems on Si substrate with different layer thicknesses. All Si layers and the deeper lying CoSi, layer are A type, whereas the crystalline orientation of the near surface layer depends on the procedure of formation. If the dose of the second implantation is too high CoSi nucleates during implantation. The CoSi precipitates are dissolved during annealing and a CoSi, surface layer of type A is formed. Additional Si implantations offer the possibility to modify the defect profile without changing .the Co distribution. During the subsequent annealing a redistribution of Co into the region of the additional defects was observed. Thus, implantation defects act as sinks for the metal atoms and play an important role during the first phase of the annealing process. 7250