Effect of γ- irradiation on structural, optical and electrical properties of thermally evaporated iron (III) chloride tetraphenylporphyrin thin films

Abstract

Influence of γ-irradiation on structural, optical and electrical properties of thermally evaporated iron (III) chloride tetraphenylporphyrin (FeTPPCl) thin films have been reported. The structural features are investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM) techniques. The optical constants of as-deposited and γ-irradiated FeTPPCl thin films have been determined in the wavelength range 200–2500nm using spectrophotometric measurements at nearly normal incidence of light. The calculated values of the absorption coefficient,α, are used to estimate the type of transitions for as-deposited and γ-irradiated FeTPPCl thin films. The real part of the refractive index in the transparent region is discussed by using a single-oscillator and Drude models. According to Millerʼs rule, the single oscillator model is used to deduce the third-order nonlinear susceptibility, χ(3). The temperature dependence of DC electrical conductivity, σDC, confirms the semiconducting behaviour of FeTPPCl thin films. A free band type in the higher temperature region and hopping type in the low-temperature region have been used to explain the DC conduction mechanisms of FeTPPCl thin films.