Kinetic study of chemical bath deposition of silver sulfide thin films

The growth kinetics of silver sulfide films chemically deposited from aqueo us silver nitrate-thiourea solutions at pH around 9 is studied as a functio n of the concentrations in solution, temperature (40 to 80 degrees C) and h ydrodynamic regime. It is found that the growth takes place in a narrow pH window (8.8 to 9.4). It is activated by temperature with an apparent activa tion energy of 20.4 kJ.mol(-1), which is coherent with a diffusion control evidenced by experiments at different hydrodynamic regimes. The overall rat e equation has been determined. The ultimate thickness of the films (around 1-2 microns) is actually limited by a parasitic process attributed to unst icking.