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

Abstract

The preferential deposition of metal nanoparticles onto periodically poled lithium niobate surfaces, whereby photogenerated electrons accumulate in accordance with local electric fields and reduce metal ions from solution, is known to depend on the intensity and wavelength of the illumination and the concentration of the solution used. Here, it is shown that for identical deposition conditions (wavelength, intensity, concentration), post-poling annealing for 10 h at 200 C modifies the surface reactivity through the reorientation of internal defect fields. Whereas silver nanoparticles deposit preferentially on the þz domains on unannealed crystals, the deposition occurs preferentially along 180 domain walls for annealed crystals. In neither case is the deposition selective; limited deposition occurs also on the unannealed -z domain surface and on both annealed domain surfaces. The observed behavior is attributed to a relaxation of the poling-induced defect frustration mediated by Li þ ion mobility during annealing, which affects the accumulation of electrons, thereby changing the surface reactivity. The evolution of the defect field with temperature is corroborated using Raman spectroscopy. V C 2016 AIP Publishing LLC. [http://dx

Hybrid Plasmonic–Ferroelectric Architectures for Lasing and SHG Processes at the Nanoscale

“…Finally, it has also been reported the possibility of shaping the organization of metallic nanostructures into predefined ferroelectric arrangements by tuning external parameters such as temperature, solution concentration, flux of photogenerated electrons (irradiation time), stoichiometry, or the irradiation photon energy . For example, increasing the temperature of the photoreduction process will decrease the magnitude of the spontaneous polarization, which leads to a larger amount of uncompensated screening charges.…”

Photoinduced Metallic Particle Growth on Single-Crystal Relaxor Ferroelectric Strontium Barium Niobate

“…In the absence of photoanodic dissolution, we consider a number of possible explanations. Preferential particle deposition on c + LiNbO 3 domains was recently attributed to the presence of defect dipoles, but it is currently unknown if a similar defect dipole state exists in SBN . Further, the single-domain state in SBN can be unstable because of domain instabilities originating from residual depolarization and internal fields. , Assuming that the majority of the c + -poled surface remains in the c + configuration but there exist nanoregions that have reverted to the unpoled state, then these sites can act as hole receptors and promote oxidation.…”

Tunable Wettability of Ferroelectric Lithium Niobate Surfaces: The Role of Engineered Microstructure and Tailored Metallic Nanostructures

“…Micro- and optofluidic devices are of interest for a wide range of applications including chemical synthesis, biological analysis, crystallization of proteins, and cell and particle sorting. − An important aspect of optimizing the materials used in such devices is the ability to tailor the wettability − by controlling the surface energy (chemical composition and surface charge) and topographical structure (surface roughness). − LiNbO 3 (LN) is widely used in optoelectronic and photonic applications due in part to its large nonlinear optical coefficients and reversible spontaneous polarization and has recently been used in micro- and optofluidic applications, which take advantage also of the piezoelectric, pyroelectric, or photovoltaic properties of the crystals. − Furthermore, LN has been shown to be cytocompatible with MC3T3 osteoblast cells and neurons, providing opportunities to use LN in biological applications. − The reversible spontaneous polarization, e.g., by electric field poling, , of LN also allows the surface charge and reactivity to be patterned, a property that has been exploited to fabricate metallic nanostructure arrays. , Proton exchange, a technique used to fabricate waveguides in LN, has also been used to engineer surface reactivity for the fabrication of metallic nanostructure arrays for Raman-based sensing of molecules. , Proton exchange of a LN surface through reactive ion etched mask openings causes additional changes to the surface topography via proton exchange induced swelling and reactive ion etch (RIE) damage. ,, LN crystals are therefore highly tunable, biocompatible substrates that present opportunities to tailor surface roughness, charge, and reactivity, factors that are expected to influence surface wettability. ,,− …”