Polycrystalline ZnO thin films both undoped and doped with various types of impurities, which covered the wide carrier concentration range of 10 16-1021 cm- 3, were prepared by magnetron sputtering, and their optical-band gaps were investigated. The experimentally measured optical band-gap shifts were analyzed by taking into account the carrier density dependent effective mass determined by the first-order nonparabolicity approximation. It was shown that the measured shifts in optical band-gaps in ZnO films doped with cationic dopants, which mainly perturb the conduction band, could be well represented by theoretical estimation in which the band-gap widening due to the band-filling effect and the band-gap renormalization due to the many-body effect derived for a weakly interacting electron-gas model were combined and the carrier density dependent effective mass was incorporated.
Bibliographical noteFunding Information:
This work was supported partially by the Korea Institute of Science and Technology (KIST) internal project under contract 2E22832 , and in part by the Converging Research Center Program through the National Research Foundation of Korea (NRF) grant ( 2009-0082023 ) funded by the Ministry of Education, Science and Technology and by the Korea Science and Engineering Foundation (KOSEF) grant ( 2009-0064868 ).
- Optical band-gap
- ZnO thin film
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry