Nanoindentation on a-plane ZnO thin films

Sheng Rui Jian, Jason Shian Ching Jang, Guo Ju Chen, Hou Guang Chen, Yuan Tsung Chen

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


The structural and mechanical properties of radio-frequency sputtering derived a-plane ZnO epilayers on r-plane sapphire substrates developed at the various deposited temperatures was systematically studied by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques. The result of XRD analysis revealed that the angle of (1 1 over(2, ̄) 0) orientation increased with the deposited temperature. Both of the surface roughness and grain size of the a-plane ZnO thin films, which investigated by AFM and XRD, exhibits an increasing trend with the deposition temperature. In addition, the hardness and Young's modulus of a-plane ZnO thin films calculated from the load-displacement curves varied with the deposition temperature accordingly. As the deposition temperature increases from 300 to 500 °C, the grain size increases from 52 to 84 nm. The hardness of a-plane ZnO thin films dropped from 8.6 to 11.3 GPa due to the increase of the grain size. Moreover, by fitting experimental data with the Hall-Petch equation, a probable lattice friction stress of 1.64 GPa and Hall-Petch constant of 66.27 GPa nm1/2 are obtained.

Original languageEnglish
Pages (from-to)348-351
Number of pages4
JournalJournal of Alloys and Compounds
Issue number1-2
StatePublished - 24 Jun 2009


  • AFM
  • Hardness
  • Nanoindentation
  • XRD
  • ZnO


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