Simulation of growth and shape of nanowires in the absence of a catalyst

The growth and morphology of semiconductor nanowires (NWs) obtained in the absence of catalyst of growth are theoretically investigated. A self-consistent model is constructed that simultaneously describes both vertical and radial growth of NWs. It is shown that the vertical growth rate nonlinearly depends on the time at the initial stage and tends to a constant value at the asymptotic stage. A classification of possible forms of NWs depending on deposition conditions is given. The results are compared to experimental data regarding the morphology of GaN nanowires obtained using molecular beam epitaxy on the silicon surface.