The effect of Mg0.1Zn0.9O layer thickness on optical band gap of ZnO/Mg0.1Zn0.9O nano-scale multilayer thin films prepared by pulsed laser deposition method

Ja Young Cho, Seung Wook Shin, Ye Bin Kwon, Hyun Ki Lee, Kyu Ung Sim, Hong Seung Kim, Jong Ha Moon, Jin Hyeok Kim

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Abstract

Epitaxial ZnO/Mg0.1Zn0.9O (MZO) nano-scale multilayer thin films were prepared on Al2O3 (0001) substrates by pulsed laser deposition. The ZnO/MZO multilayer thin films were grown by stacking alternate layers of ZnO and Mg0.1Zn0.9O with a laser fluence, repetition rate, substrate temperature and oxygen partial pressure of 3 J/cm2, 5 Hz, 600 °C and 3.8 × 10 - 7 Pa, respectively. The thickness of an individual ZnO layer was maintained at 3 nm, whereas that of the MZO layers was varied from 3 nm to 15 nm. Cross-sectional transmission electron microscopy revealed alternating layers of bright and dark contrast, indicating the formation of a ZnO/MZO multilayer. X-ray diffraction results showed that multilayer thin films were epitaxially grown as a hexagonal wurzite phase with orientation relationship of (0001)[ 101̄1]multilayer||(0001)[101̄1]substrate. The 2θ value of the (0002) peak of the ZnO/MZO multilayer thin films increased from 34.30° to 34.71°, indicating that Mg is replaced with Zn in the hexagonal lattice in the MZO of ZnO/MZO multilayer. UV-visible spectroscopy showed a systematic increase in the band gap of the ZnO/MZO multilayer thin films from 3.34 eV to 3.70 eV with increasing MZO layer thickness, which suggests that the band gap energy of a ZnO/MZO multilayer thin film can be controlled by varying the thickness of each constituent layer.

Original languageEnglish (US)
Pages (from-to)4282-4285
Number of pages4
JournalThin Solid Films
Volume519
Issue number13
DOIs
StatePublished - Apr 29 2011

Bibliographical note

Funding Information:
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology ( 2009-0088912 ).

Keywords

  • MgO
  • Multilayer
  • PLD
  • Superlattices
  • UV-detector
  • ZnMgO
  • ZnO

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