Cyclic load–displacement curves and SEM micrograph on an ‘indented’ GaSe thin film. (a) The cyclic load–displacement curves obtained at an indentation load of 20 mN for the GaSe films. Notice that both multiple ‘pop-in’ and ‘pop-out’ phenomena are observable in the load–displacement curves. (b) SEM micrograph of an ‘indented’ GaSe thin film showing the cracking (see the red arrow) along the corners and ‘pile-ups’ along the edges of the Berkovich indentation after an indentation load of 20 mN.
Jian et al. Nanoscale Research Letters 2012 7:403 doi:10.1186/1556-276X-7-403