The ionic conductivity profile of thin evaporated AgCl films on a planar sapphire substrate
Abstract The ionic conductivity profile of AgCl-films stepwise evaporated onto a sapphire-substrate has been measured. After each step the films have been annealed. A bombardment of the uncompleted films by argon-ions (just before the successive evaporation processes) enhances the ionic conductivity. The first sheet (about 350 nm thick) of these films adjacent to the interface shows extremely high conductivity values up to about 10 −4 S/cm at 25°C. But also the remaining part of each film between about 350 and 800 nm away from the interface still shows an unexpectedly good conductivity of the same magnitude as the highest conductivity value (of 6×10 −6 S/cm at 25°C) found so far for disperse systems AgCl/Al-oxide. The measureds activation energies (between 0.34 and 0.47 eV) of these films are markedly higher than the migration enthalpy of Ag-vacancies (0.28 eV). The discussion suggests that the high conductivity and its profile are essentially determined by the microscopical structure of the films.