The diffusion of Cu in ZnS thin films was investigated at 80 to 400C by using the energy-dispersive X-ray fluorescence technique. The thin films were deposited, by spray pyrolysis, onto a glass substrate. The temperature dependence of the Cu diffusion coefficient (figure 30) could be described by:

D = 1.4 x 10-10 exp[-0.18(eV)/kT]

It was shown that diffusion Cu-doping of n-type ZnS was accompanied by a significant increase in the resistivity and a slight decrease in the band-gap of the ZnS films. The observed results were attributed to the migration of Cu in polycrystalline ZnS films via diffusion along grain boundaries and into grains.

Copper Diffusion in ZnS Thin Films. E.Bacaksiz, T.D.Dzhafarov, V.D.Novruzov, K.Öztürk, M.Tomakin, T.Küçükömeroğlu, M.Altunba, E.Yanmaz, B.Abay: Physica Status Solidi A, 2004, 201[13], 2948-52