Pure bismuth samples were irradiated at 20 K with swift heavy ions from 18O to 238U in the GeV range. The rate of the induced damage was deduced from in situ electrical resistance measurements. Above a threshold in the electronic stopping power Se equal to 24 keV nm-1, the damage is due to electronic slowing down. Above 30 keV nm-1, the electronic slowing down is efficient enough to induce latent tracks attributed to the appearance of a high-resistivity phase. The induced latent tracks radii can be up to 21.9 nm for Se=51 keV nm-1 which is the largest value reported so far for non-radiolytic materials. The evolution with Se of the latent tracks radii is calculated on the basis of the thermal spike model, assuming a realistic value for the electron-phonon coupling constant. A rather good agreement is obtained which supports the idea that the thermal spike could be operative in the observed radiation damage.

The present article deals with the optimized processing conditions leading to the highest density of Si nanoclusters which play the role of sensitizing centers for the nearby Er ions within a silica matrix. The layers were obtained by reactive magnetron sputtering under a plasma of Ar mixed to different rates of hydrogen, and were subsequently annealed at various temperatures. The increase of the dilution degree of the Ar plasma with hydrogen was found to multiply the nucleation sites whose density foreshadows that of the Si nanoclusters formed upon annealing. Both hydrogen content and annealing temperature govern the growth of the clusters. The maximum density of efficient sensitizing centers was obtained for hydrogen rate in the plasma of 50% and annealing at 900 °C. This has directly led to the enhancement of the coupling rate between the Si nanoclusters and the Er ions, as reflected by the ten times increase of the proportion of optically active ions, compared to that for standard conditions. In parallel, the lifetime emission of the active Er ions was found to continuously improve with the annealing temperature and has reached values exceeding 7 ms.

Room-temperature 1.54 μm electroluminescence from Er-doped silicon-rich silicon oxide films deposited on n + -Si substrates by magnetron sputtering J. Appl. Phys. 90, 5835 (2001); 10.1063/1.1413231Effect of hydrogenation on room-temperature 1.54 μm Er 3+ photoluminescent properties of erbium-doped silicon-rich silicon oxide Er-doped Si-rich silica layers were obtained by reactive magnetron sputtering and both structural and room-temperature photoluminescence properties were investigated. The controlled introduction of hydrogen in the plasma was found to play a critical role in the microstructure and distribution of the Si nanograins formed after annealing. Concomitant density increase and size decrease of these nanograins mostly amorphous were noticed upon increasing the hydrogen partial pressure in the plasma. This was accompanied by a systematic enhancement of the Er emission indicating that both crystallized and amorphous silicon nanoparticles are similarly efficient sensitizers for Er emission. The lifetime of the latter was found as high as 5-6 ms.

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