Critical condition for growth of silicon nanowires

The existence of a critical radius on the growth of Si nanowires by the vapor-liquid-solid mechanism is examined. By varying the experimental growth parameters, we have shown a dependence of the minimum nanowires radius with the Si reactive species partial pressure, demonstrating that the critical radius is not a limited one. A thermodynamical model giving a quantitative aspect of the dependence of a critical nanowire diameter on Si supersaturation in a Au-Si droplet is proposed. These results open up a way to grow many kinds of nanowires with nanometric diameter. The size control has important implications for electronic and optical properties of nanowires based devices.