In Fig. 7a we have plotted the values of ln(R/R400) versus 1000/T for all the Sn–ZnO films. From the plot the thermal activation energy was calculated using Arrhenius formula [27].
InFig. 7a we have plotted the values of ln(R/R400) versus 1000/Tfor all the Sn–ZnO films. From the plot the thermal activation energywas calculated using Arrhenius formula [27].