Figure 1
From: Effects of substrate annealing on the gold-catalyzed growth of ZnO nanostructures
Topography of c-plane sapphire substrates after thermal annealing. 2μm × 2μm AFM images of c-plane sapphire substrate (a) as-received and after annealing at (b) 1,000°C, (c) 1,200°C and (d) 1,400°C. Insets in (b-d) show height profiles of the white lines. All AFM images use the same height scale (bottom).