Fe-doped and (Zn, Fe) co-doped CdS films: Could the Zn doping affect the concentration of Fe2+Fe2+ and the optical properties?

Cd1-xFexSCd1-xFexS and Cd1-x-yFexZnySCd1-x-yFexZnyS thin films were grown by low-pressure metal organic chemical vapor deposition (LP-MOCVD) on c-Al2O3c-Al2O3 substrates. The films fabricated at 360∘C under an hydrogen pressure of 76 Torr had hexagonal structure with only one (0 0 0 2) diffraction peak. The samples with low doping content have sharp absorption edges. It is found that the absorption edge and the emission peak positions of the Cd1-x-yFexZnySCd1-x-yFexZnyS film shift to high energy due to the Zn-doping. The band gap energy could be tuned in a wide range with the change of Zn content. The broadening of the Cd1-x-yFexZnySCd1-x-yFexZnyS emission peak could be attributed to the alloy fluctuations and the shallow defect in the samples.