Growth aspects and microscopic analyses of Pd-catalyzed InAs nanowires on the B-face of InAs (111) substrate by solid source molecular beam epitaxial method

Abstract

InAs nanowires were grown on InAs (111) substrates using Pd as a catalyst. The growth was done using solid source molecular beam epitaxy. Zinc-blende InAs nanowires with zero defects have been successfully grown along the <110> directions. This study explores the structural features of synthesized nanowires using microscopic methods. The study used various deposition parameters, including catalyst particle density, growth temperature, and the V/III precursor ratio, to examine how these factors affect the growth of nanowires. All the parameters for the growth of nanostructure significantly influence on the grown nanowires. It is found to be 15 Å thick palladium film provides the favourable catalyst particle size. Temperature-dependent growth studies exhibited the reasonable density of nanowires with orientation along <110> plane for nanowires obtained at 375 °C. The varying amounts of input precursors show that both fluxes significantly influence the growth rate and density of the collected nanowires. Less tapered nanowires are produced under low supersaturation conditions, while a high In-flux promotes axial growth, leading to increased tapering of the nanowires. The morphology of the harvested nanowires was examined using a Scanning Electron Microscope (SEM). Additionally, Transmission Electron Microscope (TEM) analysis verified that the grown nanowires have a zinc blende structure, and no catalyst signature was detected. It was also observed that the tips of these nanowires showed a nearly even distribution, containing about a 50:50 ratio of palladium and indium in their chemical makeup. The high-angle annular dark field image and the intensity profile indicate that the Zinc-blende nanowires possess outstanding defect-free characteristics, which makes them highly appropriate for spintronics applications.