Photoinduced Surface Deposition Phenomenon of Chalcogenide Amorphous Films Containing a large Amount of Silver (Studies of Nucleation and Growth Process)

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The Basic data of the nucleation and growth process were obtained for 2 years from 1999 to 2000. The samples used in this experiment were the bulk glasses in the system of Ag_xAs_<15>S_<40-x> (35≦x≦45) and the films in the system of Ag_x(Ge_<0.3>S_<0.7>)_<100-x> (55≦x≦67). The bulk glass with low Ag concentration shows small amount of segregated Ag but high density Ag particles. In contrast, the bulk glass with high Ag concentration shows large amount of segregated Ag but small density Ag particles with large size. On the other hand, the film samples with low Ag concentration shows small amount of segregated Ag and the samples with large Ag concentration shows large amount of segregated Ag. The number of Ag particles does not depend significantly on the Ag concentration. The Ag concentration affects the size of Ag particles. In fact, the illuminated area is densely covered with Ag deposits for high Ag concentration (x=65〜67), as if a continuous Ag film.The addition of nucleus former wa … More s found to be effective to increase the number of Ag particles. The addition of a small amount of Au metal is highly effective for the Ag-As-S bulk glasses. The implantation of Au^+ ions was also effective for the Ag-As-S bulk glasses. The electron beam irradiation before optical illumination was found to create high density Ag nucleus. In 2001, we have researched difference of the crystal growth mechanism between the bulk glasses and film samples. The crystal growth depends strongly depends on the Ag concentration, irrespective of the bulk glass and film sample.In summary, the following model may be proposed for the nucleation and growth process of Ag particles in the Photoinduced surface deposition phenomenon. Some nucleation site on the sample surface may assist the Ag deposition. In the case of bulk glasses, the number of sits is large for low Ag concentration and decreases with increasing the Ag concentration. This seems to be due to the glass structure. For the film sample, the site may be concerned with both surface roughness and structure of the films, since many Ag particles appear for the film samples with high Ag concentration. Both surface roughness and structure for the films may be large than for the bulk glasses. The addition of Au metal may produce the Au clusters in the glass and film and the Au cluster may act as a nucleation center of the Ag deposition process. The effect of Au cluster is significant for the bulk glass than for the film sample, the number of original site of the bulk glass is much less than the film sample. Less