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In order to improve the crystallization of APCVD silicon on amorphous substrates we have investigated different techniques to grow films with sufficient average grain size. An experimental study of the influence of substrate surface topology on nucleation and grain size of APCVD grown silicon is reported here. Oxidized silicon wafers with a striation pattern and pyramidal structure are used as substrates for deposition. The size of the striation pattern varies from 8 to 128 μm in period and from 40 nm to 36 μm in height. The pyramids and inverted pyramids (2-40 μm high) have been made using selective etching of (100) oriented wafers. A 20-50 μm thick silicon film has been deposited on all substrate types at high temperature (1100-1200°C) and SiH 2 Cl 2 partial pressure of 500 Pa. The structure of the deposited film strongly depends on the surface topology. To study the mechanism of this effect we have determined the nucleation densities on textured surfaces for a deposition time of 2 s. A value of 6-10 μm -2 was found. Although the free-energy change is lowered at the edges (E.I. Givargizov, Oriented Crystallization on Amorphous Substrates, Plenum, New York, 1991) there was no significant increase of nucleation density in these areas. Thus the effect observed is supposed to occur due to the change of geometry at competing grain growth. The described effect seems to be applicable to grow silicon films appropriate for solar cell production.

We have developed a chemically selective laser ion source at the CERN-ISOLDE facility in order to study neutron-rich Ag nuclides. A pulsed laser system with high repetition rate has been used based on high-power coppe-vapour pump lasers and dye lasers. With this source significant reductions of the isobaric background has been achieved.

The use of chemically selective laser ionization combined with beta-delayed neutron counting at ISOLDE has permitted identification and half-life measurements for 61Mn up through 69Mn. The 14(4)-ms half life for 69Mn is one of the shortest determined for any nuclide beyond the sd shell. Gamma-ray singles and coincidence spectra have been determined for the decays of 64,66Mn to levels of 64,66Fe, revealing strong deformation and vanishing of the N=40 subshell in the Fe isotopes.

In a recent experiment at CERN/ISOLDE, we have used laser isotope separation to isolate heavy Ag nuclides including the N=82 r-process “waiting-point” isotope 129Ag. A half-life of 46(+5/−9) ms for the πg9/2 ground-state decay of 129Ag could be determined using beta-delayed neutron counting. In the case of 126Ag and 128Ag decays, γ-spectroscopic techniques with time resolving multi-channel-analysers were used to identify the 2+ and 4+ levels in 126Cd and 128Cd, respectively. The hyperfine splitting of the atomic transition in Ag which is used for laser ionization has made possible an isomer selection through which the β- and γ-decay of the high-spin isomer of 122Ag were observed while suppressing the ionization of the low-spin isomer.