ZnO thin films of different thicknesses were prepared by thermal evaporation on glass substrates at room temperature. Deposition process was carried out in a vapour pressure of about $5.54 \times 10^{-5}$ mbar. The substrate–target distance was kept constant during the process. By XRD and AFM techniques the microstructural characteristics and their changes with variation in thickness were studied. Electrical resistivity and conductivity of samples vs. temperature were investigated by four-probe method. It was shown that an increase in thickness causes a decrease in activation energy.
