Influence of ammonia concentration on the structural, composition and optical properties of CdZnS thin films

This paper is a systematic study on the effects of ammonia concentration on the morphology, structure, atomic percentage of major elements and optical properties of chemical bath deposition(CBD) Sulfur-zinc-cadmium (CdZnS) semiconductor thin films. By using Ultrahigh-Resolution Scanning Microscope (SEM) and when the ammonia concentration is 0.4 M, 0.5 M and 0.6 M, The CdZnS nanoparticles on the surface of the thin film, it is observed, exhibit better compactness and uniformity and the pores on it are less. With the increase of ammonia concentration, as it is shown in EDS, the content ratio of Zn to Cd in the thin films increased slightly at first and then decrease gradually. X-ray diffraction (XRD) studies show that the crystal structure of the thin film is always hexagonal phase with increasing ammonia concentration, and the crystallinity of the film is better with higher concentration of ammonia. A research is carried out with spectrophotometer on the optical properties of the thin film, and the results show that the highest transmittance of the sample is above 85%. With the increase of ammonia concentration, it is also found, the trend of the optical band gap of the thin film is consistent with the trend of the zinc content in the EDS measurement.