Authors: V Schmidt S Senz U Gösele
Publish Date: 2005/02/01
Volume: 80, Issue: 3, Pages: 445-450
Abstract
Silicon nanowires grown epitaxially via the vapor–liquid–solid mechanism show a larger diameter at the base of the nanowire which cannot be explained by an overgrowth of the nanowire alone By considering the equilibrium condition for the contact angle of the droplet the Neumann quadrilateral relation a quasistatic model of epitaxial nanowire growth is derived It is found that a change of the contact angle of the droplet is responsible for the larger diameter of the nanowire base so that the expansion has to be considered a fundamental aspect of epitaxial vapor–liquid–solid growth By comparison of experimental results with theoretical calculations an estimate for the line tension is obtained In addition the growth model predicts the existence of two different growth modes Only within a certain range of linetension values is the mode corresponding to ordinary nanowire growth realized whereas nanowire growth stops at a relatively small height if the line tension exceeds an upper boundary An approximate analytic expression for the upper boundary as a function of the surface tensions is given
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