Structural and chemical properties of highly oriented cadmium sulfide (CdS) cauliflower films

• Published in: Chemical physics letters 2010-08, Vol.495 (4), p.232-235
• Main Authors: Vemuri, R.S., Gullapalli, S.K., Zubia, D., McClure, J.C., Ramana, C.V.
• Format: Article
• Language: English
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/j.cplett.2010.06.042

Fabrication of the highly oriented, single phase hexagonal-CdS films with a cauliflower morphology using sputter-deposition under controlled sputtering-power has been demonstrated. [Display omitted] ►CdS is an important material with a potential for a wide range of scientific and technological applications. A wide and direct band gap (∼2.42 eV) coupled with n-type conductivity makes CdS suitable for application in large area optoelectronic devices such as such as solid state lasers and detectors, window layer in hetero-junction solar cells, field-effect transistors, and photoconductors. ► Significant research efforts were directed involving higher temperatures, chemical treatments, intense pulsed-lasers to grow the single phase, oriented CdS films. In this communication, we demonstrate the room-temperature growth of high-quality H-phase CdS thin films with a very high degree of orientation along c-axis. The present work has been performed on CdS films deposited using RF magnetron sputtering, which offers the advantage in simplicity of the process, cost effectiveness, industrial scalability. Interestingly, we found that the high-structural and chemical quality H-CdS layers can be stabilized by carefully controlling the sputtering-power. The results and their implications for technology are presented and discussed in this Letter. Cadmium sulfide (CdS) films have been produced by sputter-deposition varying the sputtering-power ( P) in the range of 60–120 W. The crystal structure, morphology and chemical quality of the CdS films has been investigated employing X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray spectrometry (EDS). Structural characterization indicates that all the CdS layers exhibit cauliflower morphology. Highly oriented, single phase hexagonal-CdS films can be produced at P = 75–105 W while the films at other power contain mixed phases. Characterization using XPS and EDS indicate that the CdS layers are nearly stoichiometric at P = 75–105 W, at which point S-deficiency is induced resulting in Cd-rich-CdS layers.