Role of the buffer layer on the mechanical strength of nanowire-substrate interface

Atomic force microscopy has been utilized to study the structure and mechanical strength of the epitaxial interfaces of InAs and GaP nanowires grown on Si substrates. Measuring the elastic forces during the controlled cleavage of individual crystals carried out by lateral mechanical action of atomic force microscope probe allowed us to establish a correlation between the strength of the epitaxial interface and the level of lattice mismatch. It was shown that InAs nanowires grown on InAs buffer layer demonstrate different mechanical strength compared with the ones grown directly on Si. Meanwhile, mechanical strength of GaP nanowires grown on GaP buffer is of the same order as that of GaP nanowires grown directly on Si. Analysis of the topography after nanowire removal confirmed differences in the failure mechanisms of the interface.