The microstructure of (001) InP crystals scratched with a sharp diamond tip depends strongly on the scratching direction. The scratch surface is found to conform to the radius of curvature of the tip (∼60 nm) by the formation of atomic crystal steps produced by dislocation glide along {111} planes. 110 scratches lead to coherent local crystal lattice movement and rotation causing deep dislocation propagation into the crystal and irregular pileups at the sides of the scratch surface. 100 scratches lead to incoherent lattice movement causing dislocation locking that inhibits their propagation and results in regular pileups. © 2013 AIP Publishing LLC.