The control of the growth orientations of electrodeposited single-crystal nanowire arrays: a case study for hexagonal CdS

Abstract

The controllable growth of highly aligned and ordered semiconductor nanowire arrays is crucial for their potential applications in nanodevices. In the present study, both the growth orientation and the microstructure of hexagonal CdS nanowire arrays electrodeposited in a porous alumina template with 40 nm diameter pores have been controlled by simply tuning the deposition current density. An extremely low current density of 0.05 mA cm(-2) is favorable for the growth of single-crystal CdS nanowires along the normal direction of the intrinsic low-surface-energy (103) face. This can be understood well by a modified critical dimension model given in the present work.

Doping influence on the ability to form single crystals

“…This theoretical problem has been existing in the field of material science for many years. Although the concept of binding energy may be successful in understanding some processes of crystal growth, such as the much more difficult growth of rare gas (such as Ar or Xe) crystals [4,5] compared to crystal growth of metal, and the much easier formation of graphite structure relative to diamond structure, it fails to understand why the growth tendency of (1 0 0) faces is considerably different from that of (1 1 1) faces for the same metal crystal [6][7][8]. In principle, the phase field theory is capable of predicting the ability of materials to form single crystals [9][10][11], but the prediction needs two key parameters, the solid-liquid interfacial free energy [12,13] and kinetic coefficient [14][15][16][17], which can only be extracted from extensive molecular dynamics (MD) simulations, and massive calculations are involved in the three dimensional phase field simulation.…”

Cyanide-free preparation of gold nanowires: controlled crystallinity, crystallographic orientation and enhanced field emission

“…The formation of singlecrystalline and polycrystalline structures of Au NWs can be ascribed to a 2D layer-by-layer epitaxial mechanism and 3D nucleation-coalescence growth mechanism, respectively. 34,41,47,48 According to these two mechanisms, new grains will appear when the size of an initial cluster exceeds the critical dimension N c during the deposition process. A larger N c favours the single-crystal growth of NWs from an initial seed grain.…”

“…21,24,33 In addition, the control over crystallinity and crystallographic orientation of NWs has also been achieved. 21,24,[33][34][35] Gold possesses excellent electrical and thermal conductivities, high ductility, and chemical inertness, which has fueled a wave of research on gold NWs. 3,7,31,36 For instance, gold NWs have shown very large yield strength compared to that of bulk nanocrystalline gold ($100 times).…”

“…Using different electrolytes, pore sizes and other fabrication conditions, gold NWs featuring different crystallinity and crystallographic orientation have been reported by different research groups. 21,24,[33][34][35]40 Namely, the growth of single-crystal gold NWs was favored when gold cyanide electrolytes were used, 1,24,40 while polycrystal structures have usually been achieved by using gold sulte electrolyte. 23 For crystallographic orientation, using a cyanide electrolyte (Doduco), gold NWs with preferential orientation along the [110] direction were obtained under potentiostatic deposition and the preferential orientation changed to the [100] direction when a reverse pulse deposition was used.…”

Sn-catalyst growth and optical waveguide of ultralong CdS nanowires

“…Electrically driven and optically pumped lasing have been demonstrated in single CdS NWs and NBs [3,4,17], which may lead to great applications in nanoscale lasers and other light emission devices. Recently, a variety of 1-D CdS nanostructures have been synthesized using different methods, such as thermal evaporation growth of NTs and NBs [5,6], solution chemistry approach of NW arrays [7,8]. However, the growth of 1-D CdS nanostructure has difficulty in producing large-scale, high-quality and ultralong NWs.…”