The surface topography of cracks in strained In0.72Ga0.28P films

Cracks in a 2% tensile strained In_0.72Ga_0.28P film grown on an InP substrate by molecular-beam epitaxy have been studied by cross-section transmission electron microscopy and scanning probe microscopy. A dislocation analogue (i.e. replacing the crack by an array of equivalent infinitesimal edge dislocations) is employed to account for the ratio of the crack-opening displacement to the normal surface displacement associated with the crack.