Spray deposition of CdTe-Te thin films using ethylene-diamine-tetra-acetic acid as a complexing agent in the precursor solution

摘要

CdTe thin films have been deposited by spray pyrolysis technique using varying concentration of Ethylene-diamine-tetra-acetic acid (EDTA) as a complexing agent (CA) in the precursor solution. Scanning electron micrographs show the films deposited with EDTA have a more homogeneous distribution of fine grains. X-ray diffraction patterns show that the films consist of a mixture of CdTe and Te, the Te peaks intensity increasing with EDTA concentration. X-ray photoelectron spectroscopy study of the surface reveals that there is a change-over in chemical environment of Te from -2 to +4 state after using CA. A broad photoluminescence peak at 1.40 eV is observed in the films without CA, which can be resolved into two peaks 1.43 and 1.40 eV. The intensities of both peaks are increased with EDTA due to formation of elemental Te and Cd vacancies. Optical study indicates that an increment in optical reflection due to Te metallic cluster formation in the film. Thus, the stoichiometry of the CdTe films can be controlled by varying EDTA concentration. (C) 2003 Elsevier B.V. All rights reserved. References: 27