In Figure 3 we have reported the variation of the crystallite size as a function of doping level. As can be seen,
the crystallite size increased for undoped ZnO and doped films with increasing doping level up to 2 wt.%
Co and 3 wt.% In. In this region the values of lattice parameters c decreased (Table 1), and the strain of the
films is also decreased, indicating the strain along the caxis.