Electrostatic control of the domain switching dynamics in congruent LiNbO3 via periodic proton-exchange

Abstract

We propose a model for the poling-inhibiting action of proton-exchange, associated to nonuniform fields induced in the crystal by the vanishing of ferroelectricity in the β-phase of HxLi1−xNbO3. Predictions are corroborated by experimental results on the poling of 0.5 mm thick congruent LiNbO3 substrates with periods around 8 μm, yielding regular bulk domain structures with aspect ratios as high as 250.

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

“…22 We study here Ag nanopatterned arrays formed using Ferroelectric lithography based on periodically proton exchanged (PPE) template methods. 29 We demonstrate that the resulting Ag nanopatterned arrays support both SERS and surface enhancement of luminescence (SEL).…”

Nanoscale characterization of β-phase HxLi1−xNbO3 layers by piezoresponse force microscopy

“…5,8] lm, adjusted by controlling the exposure time to benzoic acid), on both þz and Àz surfaces, demonstrating the possibility to readily visualize b-phase PE regions with nanoscale resolutions, without resorting to any etching. A good agreement was consistently found between optical (n e ) and PFM (d 33 ) results, providing evidence for a direct link between the local increase of the extraordinary refractive index and the decrease of the spontaneous polarization in PE layers (Dn e / À DP s ), as originally suggested in Ref.…”

“…1(d) where we plot the calculated x-z distribution of the electrostatic field arising from the discontinuity of the spontaneous polarization (P s ) at the PE:LN boundary. 8 The contrast in Fig. 1(c) maps with good fidelity the E-field intensity pattern of Fig.…”

“…9 It was originally devised for integrated optics, 10 but it also opens up possibilities for domain engineering and ferroelectric lithography on LN substrates. 5,8,11,12 Conventional characterizations of PE in LN, made by optical techniques 13,14 are inherently limited in their spatial resolutions by beam cross-sections (in the micrometric range), while alternative methods, which can enable nanoscale imaging, are often cumbersome and destructive. 15,16 On the other hand, as LN technology is pushed to the nanoscale in 3D device engineering, 5,17 non-destructive and highresolution characterizations of the material properties become essential.…”

“…5,6 All of the above properties are (directly or indirectly) 7 related to the elevated spontaneous polarization ($75 lC/cm 2 ) of the material, which can be patterned by electric field poling and chemical techniques. 4,8 Proton exchange (PE) is a process relying on the controlled introduction of protons in LN via a thermally activated ion-exchange (H þ $Li þ ). 9 It was originally devised for integrated optics, 10 but it also opens up possibilities for domain engineering and ferroelectric lithography on LN substrates.…”