Fracture mechanisms of GaAs under nanoscratching

Abstract

ABSTRACTNanoscratching on GaAs (001) by a pyramidal diamond tip (Berkovitch) indenter has been carried on under different loads, scratching velocities and directions. Plastic deformation and fractures induced by scratching have been investigated by atomic force microscopy (AFM), and by scanning and transmission electron microscopy (SEM and TEM, respectively). Surface images revealed radial and surface tensile cracks. Focused ion beam (FIB) milling of the contact area revealed median and shear fracture distribution in the volume. The different cracks were characterized for various scratching conditions in terms of their direction of propagation, extension and frequencies. Plastic deformations have been characterized by vertical displacement of material. No purely ductile zone was observed, GaAs deformation occurred by fractures and plastic strain. Their preponderances are discussed in terms of material properties.