Issue Eur. Phys. J. Appl. Phys. Volume 44, Number 2, November 2008 Page(s) 137 - 141 Section Surfaces, Interfaces and Films DOI 10.1051/epjap:2008159 Published online 25 September 2008

Eur. Phys. J. Appl. Phys. 44, 137-141 (2008)
DOI: 10.1051/epjap:2008159

Ellipsometrically determination of the optical constants of ZnO in ZnO/Ag/ZnO multilayer system

S.H. Mohamed and S.A. Ahmed

Physics Department, Faculty of Science, Sohag University, 82524 Sohag, Egypt

abo_95@yahoo.com

Received: 19 March 2008 / Received in final form: 19 May 2008 / Accepted: 27 June 2008 / Published online: 25 September 2008

Abstract
The variable angle spectroscopic ellipsometer in conjunction with computer simulation were employed to determine the optical constants of ZnO in the ZnO/Ag/ZnO (ZAZ) multilayer system. A five-phase, glass/ZnO/Ag/ZnO/air, model was used to fit the calculated data to the experimental spectra. The ellipsometrically determined ZnO and Ag layers thicknesses were found to be agreed well with those previously determined by X-ray reflectivity. The effects of Ag layer thickness (Ag_d) and ZnO top layer thickness (ZnO_d) on the optical constants of ZnO in the ZAZ multilayer system were discussed. The refractive index values determined at 550 nm, remains almost constant as Ag_d increases while the refractive index values decrease with decreasing ZnO_d. Over the whole visible spectral range the extinction coefficient values of the Ag_d group are very close to zero and does not depend on Ag_d while the extinction coefficient values of the ZnO_d group increase with decreasing ZnO_d. The optical band gap values are found to be affected strongly by both Ag_d and ZnO_d.

PACS
78.66.-w - Optical properties of specific thin films.
78.67.Pt - Multilayers; superlattices.

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