Controlled Morphologies of Nanostructured ZnO Films by MOCVD Method

2014 ◽  
Vol 492 ◽  
pp. 311-315
Author(s):  
Bashir Ahmmad ◽  
Kensaku Kanomata ◽  
Fumihiko Hirose

Metal-organic chemical vapor deposition (MOCVD) method has been applied to grow nanostructured ZnO films on Si (100) substrate at temperatures ranging from 200 to 550 °C. The as-prepared films were characterized by XRD, SEM, XPS analysis. The growth rate of ZnO films increases with increasing the deposition temperatures. The deposition temperatures have a drastic effect on the crystallinity and morphology of the nanostructured ZnO. Whisker shaped ZnO is formed at a temperature of 350 °C. The deposition time also affects the morphology of the particles. At 400 °C, sample with one hour deposition forms whisker shaped ZnO nanostructures whereas that of with two hours deposition forms flower-like nanostructures.

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Heon Lee ◽  
Sung Hoon Park ◽  
Young-Kwon Park ◽  
Sun-Jae Kim ◽  
Byung-Hoon Kim ◽  
...  

Hierarchically structured TiO2photocatalyst films were synthesized using low-pressure metal-organic chemical vapor deposition (LPMOCVD) method to examine their photocatalytic activity. The thickness of the TiO2films increased proportionally with increasing deposition time. The TiO2film synthesized at 773 K showed a hierarchical structure composed of vertically grown laminar (112)-oriented anatase crystals. With increasing deposition time, the grain became larger and the morphology became sharper. In the initial CVD stage, small particular crystals were formed, above which sequential growth of layers of columnars with increasing size took place, forming hierarchical structure. The hierarchically structured TiO2film exhibited much higher photocatalytic activity than unhierarchically structured TiO2film. The photocatalytic activity increased with increasing film thickness.


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