Silver and gold doping of SiO2 glass by solid-state field-assisted diffusion

In this work, a solid-state field-assisted diffusion technique is used to induce diffusion of silver or gold ions into a silica matrix. The obtained systems are characterized by secondary ion mass spectrometry and Rutherford backscattering spectrometry. The metal/glass interface chemistry plays an important role in the behavior of the metals and, especially for Ag, a proper time is required for the deposited film to first oxidize and then diffuse into the matrix, owing to the external electric field. Diffusion of Ag in silica is observed to be very sensitive to the applied field at relatively high temperatures, being stopped when a high field value is applied. This behavior may be attributed to the low availability of sites and the build-up of local electric fields within the glass. As for gold, a quite peculiar behavior of the current density during the process was recorded, indicating that its behavior is even more complex than one could expect. In general, the presented preliminary experimental observations demonstrate the potential of the technique.