The calculate of optical gap energy and urbach energy of Ni1−xCoxO thin films

Abstract

The effect of Co doping on optical, structural and electrical properties of Ni1−xCoxO thin films has been successfully deposited on glass substrate by Sol–Gel Sping coating technique. The main objective of this research is to study the Ni1−xCoxO thin films to determine the optical gap energy by various methods and compare of calculated values. The transmission spectra show that the Ni1−xCoxO thin films have a good optical transparency in the visible region. The optical gap energy was varied between 3.8 and 4.05 eV, which was determined by various methods and equations. These are found in the drawn of A, A2, α, α2 (Ahν)2 and (αhν)2 as a function of the photon energy hν, the suitable method to calculate the optical energy was observed for (Ahν)2 versus hν, but this method can not be related to the film thickness. The urbach energy of the Ni1−xCoxO thin films also was determined by the curves of LnA and Lnα as a function of photon energy hν. The deduce by LnA versus hν is also suitable to estimate the urbach energy. However, the Ni0.96Co0.04O thin films have a few defects with minimum value of urbach energy. XRD patterns of the Ni1−xCoxO thin films indicate that some films are polycrystalline with cubic structure. The electrical conductivity of our films is in the order of 8.2*10−3(Ω.cm)1.