Atomistics of vapour–liquid–solid nanowire growth

Abstract

Vapour–liquid–solid route and its variants are routinely used for scalable synthesis of semiconducting nanowires, yet the fundamental growth processes remain unknown. Here we employ atomic-scale computations based on model potentials to study the stability and growth of gold-catalysed silicon nanowires. Equilibrium studies uncover segregation at the solid-like surface of the catalyst particle, a liquid AuSi droplet, and a silicon-rich droplet–nanowire interface enveloped by heterogeneous truncating facets. Supersaturation of the droplets leads to rapid one-dimensional growth on the truncating facets and much slower nucleation-controlled two-dimensional growth on the main facet. Surface diffusion is suppressed and the excess Si flux occurs through the droplet bulk which, together with the Si-rich interface and contact line, lowers the nucleation barrier on the main facet. The ensuing step flow is modified by Au diffusion away from the step edges. Our study highlights key interfacial characteristics for morphological and compositional control of semiconducting nanowire arrays.

Diameter-Controlled Germanium Nanowires with Lamellar Twinning and Polytypes

“…[1][2][3][4][5][6][7][8] The integration of semiconductor nanowires into device geometries 9 requires control over their morphology, dimensions, growth orientation, crystal phase and structural defects. Catalytic bottom-up approaches, such as vapor-liquid-solid (VLS) [10][11][12] , vapor-solid-solid (VSS) [13][14] , supercritical fluid-liquid-solid (SFLS) [15][16][17] techniques, are popular routes for growing high-aspect ratio one-dimensional nanostructures [18][19] , where nanowire diameters can be controlled by the dimension of the catalysts. 20 Control over nanowire diameters, in turn, facilitates regulation over their growth orientation.…”

The structural and optical properties of black silicon by inductively coupled plasma reactive ion etching

“…Except for porous silicon obtained by electrochemical etching, 3,4 most of the produced structures exhibit tapered profiles that result in reduced interface reflection for incident light. 5,6 While structures fabricated by the vapor-liquid-solid (VLS) approach 7,8 or by wet-chemical catalytic etching [9][10][11] are usually called "silicon nanowires," structures obtained by repeated pulsed laser irradiation 12,13 or dry etching 14,15 are typically referred to as "Black Silicon." Comparing the different attempts of nanostructure formation, the last-mentioned dry etching method exhibits some distinct advantages.…”

A surface curvature oscillation model for vapour–liquid–solid growth of periodic one-dimensional nanostructures

“…Highly anisotropic growth along the wire direction relative to the radial direction leads to the formation of 1D structures. In contrast, we would like to point out that while the main emphasis of the present work is on the size effects on growth oscillation, there are cases where other factors such as crystallography are important [27][28][29][30] . Theoretically, such crystallography effects could also be considered via the terms m s and A l-s in equation (4).…”

“…Now we investigate how this SCO modulates nanowire growth by considering growth kinetics. We first consider the evolution of the nanowire's radius, r. In a nanowire growth experiment, change in r is generally slower than the change in the nanowire's length, L. In the conventional VLS model, this is explained by considering the relative growth rates of different crystallographic planes [27][28][29][30] . Highly anisotropic growth along the wire direction relative to the radial direction leads to the formation of 1D structures.…”