Fabrication and characterization of nanowire arrays on InP(100) surfaces
This work investigates the technique of mass fabrication of nanowires on semiconductor InP (100) surfaces by low energy Ar+ ion beam bombardment. Systematic investigation shows that under some crucial experimental parameters, nanowire arrays of regular periodicity can be produced. An ambient Atomic Force Microscope was used in contact mode to examine the morphology of the irradiated InP surfaces. The chemical composition of the irradiated samples was characterized by X-ray Photoelectron Spectroscopy (XPS). The electronic structure of the fabricated nanowire arrays was jointly explored by Scanning Tunnelling Spectroscopy and XPS. The research shows that In enriched ripples and nanowires form under prolonged irradiation by Ar+ ions due to preferential sputtering of P from InP under grazing ion incident angle above some crucial irradiation ion dose. A model of mergence from tailed cones is proposed to account for the formation of these ripples and nanowires. The drive to the formation of periodic ripples and nanowires is believed to be stress-field induced self-organisation of strained cones. The cone-mergence model is a combination of the model of stress-field induced self-organization and the model of ripple topography by Bradley and Harper (BH). The research proposes that the mobility of atoms on the corresponding solid surfaces under ion bombardment decides whether the surface morphology is generated by the stress-field, the BH, or a combination of the two models. Monte-Carlo simulation was used to evaluate the effect of surface damage and preferential sputtering of P from InP and N from Si3N4. The calculations predict that P and N can be preferentially sputtered from InP and Si3N4 surfaces.