p-Type transparent Cu doped ZnS thin films by the chemical bath deposition method

Transparent and well adhered Cu doped ZnS films were obtained on glass substrates by the chemical bath deposition process. The resulting films were prepared with reaction solutions containing Zn and Cu salts, ethylenediamine tetra-acetic acid disodium and thiocetamide. An analysis derived from Raman spectroscopy revealed the presence of the cubic structure or β-ZnS in the ZnS:Cu films, with an impurity phase corresponding to the insertion of Cu ions in interstitial sites or defects of the lattice. The presence of Cu in these films, formed by elongated aggregates instead of the rounded ones shown by the undoped ZnS films, was also confirmed by energy dispersive spectrometry. Changes in the optical properties as well as in the resistivity of the films have been observed due to the incorporation of Cu. In addition, it was confirmed by the rectification method that the ZnS:Cu films have p-type conductivity.