ZnO ince filmlerin kalınlıkları ve optiksel sabitlerinin noktasal kısıtlamasız minimizasyon algoritması ile belirlenmesi

Authors : Nilgün ERARSLAN, Tayyar GÜNGÖR

Pages : 181-193

View : 19 | Download : 10

Publication Date : 2010-12-01

Article Type : Research Paper

Abstract :Optical constants such as the optical band gap insert ignore into journalissuearticles values(Eg); and absorption coefficient αinsert ignore into journalissuearticles values(λ);, film thickness insert ignore into journalissuearticles values(t); and film refractive index ninsert ignore into journalissuearticles values(λ); could be computed from transmittance and/or reflectance spectra for thin film on the transparent substrate. The envelope method considering the curve through the extreme points instead of entire spectrum is much preffered method when the spectrum contain finite interference fringes for the given wavelength range depending on the refractive index insert ignore into journalissuearticles values(n); and thickness insert ignore into journalissuearticles values(t); product. However, this method can not be used in the case of insufficient number of interference fringes or no fringes and for the interference fringes with too little depth. In this case, the other methods should be used to minimize the difference between the measured and the predicted optical transmittance and / or reflection values. Pointwise Unconstrained Minimization Algorithm insert ignore into journalissuearticles values(PUMA); is the one of the methods. The refractive index insert ignore into journalissuearticles values(n); and extinction coefficient insert ignore into journalissuearticles values(κ); films and film thickness insert ignore into journalissuearticles values(t); can be calculated using this method by taking into account the entire spectrum. In this study, the validity of the PUMA method was tested on the ZnO thin films with different thicknesses prepared by spray pyrolysis.
Keywords : Optical transmittance, optical constants, PUMA