engleski

Electric field assisted dissolution of Al and Cu metal thin films

Metal doped silica glass is widely used in photonics, photoelectronis, optics as well as in sensing. There are several methods for doping the glass matrix with metal ions, such as often used melted salt ion exchange and much cheaper and simpler process called electric field assisted dissolution (EFAD), used in our laboratory 1-3. In EFAD process, thin metal films deposited on glass substrate by electron beam evaporation are subjected to moderately elevated temperature and DC voltages. Resulting current induces several consecutive processes: 1) drifting of naturally present alkali metal ions in glass matrix toward cathode, leaving the subanodic layer depleted of charge carriers ; 2) dissolution of thin metal film and 3) subsequent travelling of dissolved metal ions into the subanodic layer. Unfortunately, the doping process is still not completely unveiled. Therefore, the elucidation of the process itself is extremely important. Herein we present ellipsometry based results of the optical properties of Al or Cu EFAD doped glass. Doping with metal ions and depletion from alkali ions are processes that take place simultaneously, but each with its own dynamics. As a consequence, the refractive index in the subsurface layer of the EFAD doped glass changes with the course of the process. Besides this, the refractive index is not constant through the thickness of the affected region since concentration of the dopant metal ions, as well as alkali ions, is not homogeneously distributed.

electric field assisted dissolution ; metal thin films

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