Effects of Anions in Electrodeposition Baths on Morphologies of Zinc Oxide Thin Films

Abstract

Zinc oxide thin films were prepared in electrodeposition baths with three electrodes. The work electrode is a silicon substrate coated with Pd metal by sensitization and activization process. The work electrode is kept at -1.9 voltage v.s saturated calomel electrode. The electrodeposition baths contain ZnCl2 (4 mM) and KCl (50 mM) as host composition. The K2SO4, KNO3, and CH3COOK were respectively added into baths for studying the effects of SO42-, NO3-, and CH3COO- anions on the morphologies of zinc oxides. A scanning electron microscope was used to view the morphologies of various zinc oxides. The results showed that the shape of zinc oxide deposited in baths of ZnCl2 (4 mM) + KCl (10~100 mM), and ZnCl2 (4mM) + KCl (50 mM) + KNO3 (1~50 mM) is hexagonal pillar and when baths are ZnCl2 (4 mM) + KCl (50 mM) with addition of K2SO4 and CH3COOK the zinc oxides became curved sheets and hexagonal plates. A formation mechanism for the zinc oxide with different shapes was also proposed and discussed in this work.