The determination of urbach energy and optical gap energy by many methods for Zn doped NiO thin films fabricant semiconductor by spray pyrolysis

Abstract

The effect of Zn doping on optical, structural and electrical properties of Ni1-xZnxO thin films has been successfully deposited on glass substrate by Spray Pyrolysis technique. The main objective of this research is to study the Ni1-xZnxO thin films to determine the optical gap energy by various methods and compare it with calculated values. The transmission spectra shows that the Ni1-xZnxO thin films have a good optical transparency in the visible region. The optical gap energy varied between 3.50 and 3.75 eV, which was determined by various methods and equations. they are explained in the curves of A, A2 , α, α2 (Ahυ) 2 and (αhυ) 2 as a function of the photon energy hυ. We observed that the suitable method to calculate the optical gap energy is (Ahυ) 2 versus hυ, but this method can't be related to the film thickness. The urbach energy of the Ni1-xZnxO thin films also was determined by the curves of LnA and Lnα as a function of photon energy hυ. We deduced that LnA versus hυ is also suitable to estimate the urbach energy. However, the Ni0.90Zn0.10O thin films have a few defects with minimum value of urbach energy. The Ni0.90Zn0.10O thin films have maximum value of optical gap energy. XRD patterns of the Ni1-xZnxO thin films indicate that films are polycrystalline with cubic structure. The electrical conductivity of our films is in the order of 9*10-3 (Ω.cm)-1 .