Observation of size dependent liquidus depression in the growth of InAs nanowires

InAs nanowires have been grown in the temperature range of 400-660 degrees C in a closed vapor growth system. Due to the nature of the growth process, no transport gas or reactive gas was used. We have performed EDS analysis on the gold alloy tips of nanowires with diameters of 25, 35, 40, 60 and 100 nm. If one considers the bulk equilibrium phase diagram, our results would indicate that while the tips for the 100 nm nanowires are in a complete liquid state, those of 60 nm diameter or less are in varying degrees of partial liquid state, and the tips of wires grown at 400 degrees C would be expected to be in the solid state. However, combining the chemical analysis and low temperature results, our results suggests a significant size dependent melting point reduction in these nanowires, in excess of that predicted by the Gibbs-Thompson theory. Under these conditions, all of the nanowire tips would fall within the liquid phase and the growth of all the InAs nanowires at these temperatures can be attributed to the VLS growth mechanism. (c) 2006 Elsevier B.V. All rights reserved.