Nano Express

Nanoscale Research Letters

, Volume 4, Issue 4, pp 377-384

Open Access This content is freely available online to anyone, anywhere at any time.

Effects of Growth Conditions on Structural Properties of ZnO Nanostructures on Sapphire Substrate by Metal–Organic Chemical Vapor Deposition

  • C. C. WuAffiliated withDepartment of Materials Science and Engineering, National Chung Hsing University
  • , D. S. WuuAffiliated withDepartment of Materials Science and Engineering, National Chung Hsing University Email author 
  • , P. R. LinAffiliated withDepartment of Materials Science and Engineering, National Chung Hsing University
  • , T. N. ChenAffiliated withDepartment of Materials Science and Engineering, National Chung Hsing University
  • , R. H. HorngAffiliated withInstitute of Precision Engineering, National Chung Hsing University

Abstract

ZnO was grown on sapphire substrate by metal–organic chemical vapor deposition using the diethylzinc (DEZn) and oxygen (O2) as source chemicals at 500 °C. Influences of the chamber pressure and O2/DEZn ratio on the ZnO structural properties were discussed. It was found that the chamber pressure has significant effects on the morphology of ZnO and could result in various structures of ZnO including pyramid-like, worm-like, and columnar grain. When the chamber pressure was kept at 10 Torr, the lowest full width at half-maximum of ZnO (002) of 175 arc second can be obtained. On the other hand, by lowering the DEZn flow rate, the crystal quality of ZnO can be improved. Under high DEZn flow rate, the ZnO nanowall-network structures were found to grow vertically on the sapphire substrate without using any metal catalysts. It suggests that higher DEZn flow rate promotes three-dimensional growth mode resulting in increased surface roughness. Therefore, some tip on the ZnO surface could act as nucleation site. In this work, the growth process of our ZnO nanowall networks is said to follow the self-catalyzed growth mechanism under high-DEZn flow rate.

Keywords

ZnO Chamber pressure O2/DEZn ratio Nanowall networks Self-catalyzed