Figure 4: Growth behaviors in terms of the diameter and length of ZnO nanorods grown at 700°C for different durations of 1, 5, 30, 120 min on (a) Sn/Ni- and (b) Sn/In-coated sapphire substrates by a thermal evaporation-oxidation method with a Zn mixture of Zn and ZnO in a weight ratio of 1 : 1. The variations of axial and radial rates, obtained by curve fitting the 5-, 30, and 120-min data followed by retrieving from the derivatives of the best-fitting equations, with growth duration are shown in (c) and (d), respectively.