Effect of complexing agent on spray deposited CdTe thin films

Te rich CdTe thin films have been prepared by spray pyrolysis technique using a complexing agent ethylene-diamine-tetra-acetic acid (EDTA) in the precursor solution. The films are characterized using XRD, XPS and PL techniques. XRD studies indicates that the films consist of a mixture of CdTe and Te and the Te peak intensity varies with EDTA concentration. XPS study infers that there is a change over in chemical environment of Te. A broad photoluminescence peak at 1.40 eV is observed in the films with no complexing agent, which can be resolved into two peaks 1.43 and 1.40 eV. The intensities of both peaks increases with EDTA concentration. The stoichiometry in the films can be controlled by varying EDTA concentration, which is because of Cd ions forming stable complexes with EDTA. This hinders the CdTe formation and leaves Te in the elemental form.