Structural and Optical Characteristics of ZnS/CdS Powders and Thin Films

Chang, Ki-Seog

Journal of the Korea Institute of Military Science and Technology 2010;13(4):659-664.

Ki-Seog Chang

Korea Air Force Academy

ZnS/CdS 분말과 박막의 구조 및 광학적 특성

장기석

공군사관학교

Abstract

The ZnS/CdS thin films were made using 99.99% ZnS and CdS(Aldrich) powders in $7{ imes}10^{-6}torr$. The ZnS layer was coated over the CdS layer on an AlOx membrane within a vacuum, at the average speed of $1{AA}/sec$. After studying the ZnS/CdS and CdS thin films(both with the dimensions of 2.52nm), using fluorescence spectroscopy and comparing the respective results together, we found that although both of the resulting spectra peaked at 390nm, the ZnS/CdS thin films showed a narrower peak, and a higher intensity of photoluminescence than the CdS thin films. The particles of ZnS/CdS thin films also proved to be more homogeneous in size. In addition, the ZnS layer acted as a protective layer. Also, after studying the spectra of ZnS/CdS thin films taken 30 days after their preparation, we found no signs of aging. These results were verified through the scanning electron microscopy(SEM), EDX analysis, thin film X-ray diffraction, and luminescence spectroscopy.

Key Words: Vacuum Coating Technique, Fluorescence Spectroscopy, CdS Wurtzite Nanostructures