Enhanced redshift of the optical band gap in Sn-doped ZnO free standing films using the sol-gel method

Kam Chuen Yung, H. Liem, H. S. Choy

Research output: Journal article publicationJournal articleAcademic researchpeer-review

69 Citations (Scopus)


The optical band gap in free standing transparent zinc oxide (ZnO) films using the sol-gel method was studied. The effect of Sn doping on grain size, vibrational structure and on the optical properties of ZnO films was investigated. Contrary to the common observation, the optical band gap of Sn-doped ZnO is red-shifted from 3.38 to 3.18 eV as the doping weight percentage is increased to 3%. The redshift of the optical band gap is due to the deep states in the band gap, and a change of ∼0.2 eV can only be observed when a substrate is not used. This study illustrates that removal of interaction between film boundaries and substrate is essential for developing effective band gap-tunable ZnO thin films.
Original languageEnglish
Article number185002
JournalJournal of Physics D: Applied Physics
Issue number18
Publication statusPublished - 17 Sep 2009

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials
  • Acoustics and Ultrasonics
  • Surfaces, Coatings and Films

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