Fig. 1
Experimental observations of an annealed Ni film on sapphire. a Atomic force microscopy (AFM) topography image of a Ni film on sapphire after heat treatment, showing sunken grains with (turquoise arrow) and without (magenta arrow) an elevated ridge around the edges. b A linear topographic profile across the hole indicated using a turquoise arrow in a showing a Ni ridge at the perimeter of the sunken grain. c 3-D image of the same hole showing an elevated ridge surrounding the sunken grain. d A linear topographic profile across the hole indicated using the magenta arrow in a showing no measurable ridge formation. e 3-D image around the same hole showing a depression left by grain sinking
