Fabrication of metallic nanowires on a ferroelectric template via photochemical reaction

Abstract

Fabrication of silver nanowires on a domain-patterned lithium niobate template by inducing a photochemical reaction in an aqueous solution is reported. Silver deposition occurs preferentially along the domain boundaries which separate antiparallel domains. The nanowires can reach lengths of hundreds of micrometres, and their location can be controlled by generating domain patterns of a desired configuration while their width depends on deposition conditions, such as temperature, solution concentration and ultraviolet (UV) light exposure time. The selective deposition process is explained by a combination of the inhomogeneous distribution of the electric field in the vicinity of the domain wall and the polarization screening mechanism of the template material. Controllable and selective deposition of metal species onto nanoscale domain-patterned ferroelectric templates may provide an alternative bottom-up route to lithographic fabrication methods.

Influence of annealing on the photodeposition of silver on periodically poled lithium niobate

“…The Ag deposition is more pronounced at the 180 domain walls, in agreement with the previous reports. 14,25,26 The average relative height of the Ag nanowires, determined from line profiles, is 4.96 6 0.95 nm. However, from the AFM images and line profile in Fig.…”

“…The presence of this defect dipole can lead to increased band bending. 14 The resulting asymmetry in internal electric fields and corresponding electromechanical strains can be detected with Raman spectroscopy even a year after poling.…”

“…8,9,11,12 LN has proven to be an exception to this rule, whereby the metal particles have been found to deposit in some cases along the domain wall and on positive and negative domains in others, depending on the experimental conditions. 14,15,[22][23][24][25][26] Dunn and Tiwari have suggested that photoelectrically generated electrons can reduce the Ag þ bound to the negative surfaces and that the differences between reported results on positive domains and domain walls can be attributed to the wavelength and power of irradiation used, i.e., high power illumination creates a high flux of photons, which leads to complete domain coverage, whereas nucleation occurs only at 180 domain boundaries under low power illumination conditions. 24 Similarly, Sun et al have reported that the differences in deposition on periodically poled LN (PPLN) are due to the ratio between the photon flux and the ion flux, which can be controlled via the illumination intensity and concentration of Ag þ ions, respectively.…”

Surface enhanced luminescence and Raman scattering from ferroelectrically defined Ag nanopatterned arrays

“…15 Ferroelectric lithography is an approach based on patterning the spontaneous polarization inside ferroelectric crystals so as to engineer static electric field distributions, suitable for driving bottom-up assembly and nanodeposition at the surface of ferroelectric templates. 16 Besides electric field poling, 17 the spontaneous polarization in materials such as LiNbO 3 , can be modified through the chemical process of proton exchange. 18 This method accounts for a change in crystal lattice of the ferroelectric substrate creating a modification to the polarization and charge at the surface.…”

“…[23][24][25] The nanopatterned features created using Ag nanoparticles possessed a uniform distribution with a size variation between 2 and 10 nm in both diameter and height. 24 Photochemical reduction on LiNbO 3 has been shown under certain conditions to result in nanopatterns which form along domain walls, 17 which have further been shown to be conducting. 26 Dunn and Tiwari have demonstrated photochemical reduction on both þZ and ÀZ surfaces, and have demonstrated that the power of the irradiation is a critical parameter.…”