Nanoscale surface domain formation on the +z face of lithium niobate by pulsed UV laser illumination

Single-crystal congruent lithium niobate samples have been illuminated on the +z crystal face by pulsed ultraviolet laser wavelengths below (248 nm) and around (298-329 nm) the absorption edge. Following exposure, etching with hydrofluoric acid reveals highly regular precise domain-like features of widths ~150-300 nm, exhibiting distinct three-fold symmetry. Examination of illuminated unetched areas by scanning force microscopy shows a corresponding contrast in piezoelectric response. These observations indicate the formation of nanoscale ferroelectric surface domains, whose depth has been measured via focused ion beam milling to be ~2 micron. We envisage this direct optical poling technique as a viable route to precision domain-engineered structures for waveguide and other surface applications

Nanoscale surface domain formation on the +z face of lithium niobate by pulsed UV laser illumination

Single-crystal congruent lithium niobate samples have been illuminated on the +z crystal face by pulsed ultraviolet laser wavelengths below (248 nm) and around (298-329 nm) the absorption edge. Following exposure, etching with hydrofluoric acid reveals highly regular precise domain-like features of widths ~150-300 nm, exhibiting distinct three-fold symmetry. Examination of illuminated unetched areas by scanning force microscopy shows a corresponding contrast in piezoelectric response. These observations indicate the formation of nanoscale ferroelectric surface domains, whose depth has been measured via focused ion beam milling to be ~2 micron. We envisage this direct optical poling technique as a viable route to precision domain-engineered structures for waveguide and other surface applications

Nano-scale ultraviolet laser-induced ferroelectric surface domains in lithium niobate

Microstructuring of ferroelectric domain patterns is necessary to achieve quasi-phase-matching (QPM) in nonlinear crystals for efficient frequency conversion. The preferred method for engineering the domain structure in lithium niobate is currently electric field poling, where a lithographically-defined electrode pattern on a z crystalline face delivers a large electric field in excess of the coercive field, forming a spatially selective domain-inverted pattern within the crystal

Ultraviolet laser induced sub-micron periodic domain formation in congruent undoped lithium niobate crystals

We report the formation of ordered sub-micron periodic surface domains on the -z face of congruent undoped lithium niobate single crystals induced by pulsed ultraviolet laser illumination of the sample faces under specific irradiation conditions. We demonstrate the utility of this simple light-induced technique for achieving periodic domain inversion and investigate the nature and spatial structure of these nano-domains by scanning force microscopy. We also demonstrate subsequent re-inversion of a small region of these light-induced nano-domains using scanning force microscopy

Light-induced domain engineering in ferroelectrics

Fabrication of periodically inverted domain patterns in ferroelectric materials such as lithium niobate has been widely researched for the realisation of applications as diverse as quasi-phase-matched (QPM) non-linear devices, electro-optic Bragg deflectors, photonic band-gap structures, and piezoelectric devices such as micro-resonators, atom traps and micro-cavities. In order to overcome the limitations associated with E-field poling, we have been investigating the feasibility of a relatively simple single-step technique, which exploits the interaction of intense laser light with ferroelectric lithium niobate to engineer domains at micron and sub-micron scale-lengths. Some light-assisted poling experiments which take advantage of the ultraviolet light-induced transient change in the coercive field of the illuminated ferroelectric material to transfer a patterned light distribution into an equivalent domain structure in bulk crystals have already been reported for lithium tantalate and lithium niobate crystals. In this letter we report a direct optical poling technique that employs pulsed ultraviolet laser light to induce surface domain inversion in undoped lithium niobate in a single step. We further characterize the laser modified domain manipulated crystals using differential chemical etching and scanning force microscopy (SFM)

Photothermal alternative to device fabrication using atomic precision advanced manufacturing techniques

The attachment of dopant precursor molecules to depassivated areas of hydrogen-terminated silicon templated with a scanning tunneling microscope (STM) has been used to create electronic devices with subnanometer precision, typically for quantum physics experiments. This process, which we call atomic precision advanced manufacturing (APAM), dopes silicon beyond the solid-solubility limit and produces electrical and optical characteristics that may also be useful for microelectronic and plasmonic applications. However, scanned probe lithography lacks the throughput required to develop more sophisticated applications. Here, we demonstrate and characterize an APAM device workflow where scanned probe lithography of the atomic layer resist has been replaced by photolithography. An ultraviolet laser is shown to locally and controllably heat silicon above the temperature required for hydrogen depassivation on a nanosecond timescale, a process resistant to under- and overexposure. STM images indicate a narrow range of energy density where the surface is both depassivated and undamaged. Modeling that accounts for photothermal heating and the subsequent hydrogen desorption kinetics suggests that the silicon surface temperatures reached in our patterning process exceed those required for hydrogen removal in temperature-programmed desorption experiments. A phosphorus-doped van der Pauw structure made by sequentially photodepassivating a predefined area and then exposing it to phosphine is found to have a similar mobility and higher carrier density compared with devices patterned by STM. Lastly, it is also demonstrated that photodepassivation and precursor exposure steps may be performed concomitantly, a potential route to enabling APAM outside of ultrahigh vacuum. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Stochastic ferroelectric switching of lead zirconate titanate thin films

We investigate the repolarization phenomenon in a ferroelectric film. Our ferroelectric sample was lead zirconate titanate (PZT) obtained by sol-gel synthesis and deposited by spin coating on ITO/glass substrate. A series of repolarizations were induced in the ferroelectric film by applying a triangular wave and the current peaks related to the switchings of the ferroelectric domains were acquired for statistical analyses. It is shown that the dynamics and statistics of polarization switchings are well simulated by a simple mean-field model in which a double-well, asymmetric potential is included to describe the asymmetry at the PZT-ITO interface

Effect of piezomagnetism on coupling of electric and magnetic domain walls in hexagonal manganites

The profiles of antiferromagnetic domain walls in hexagonal manganites RMnO 3 are obtained numerically depending on anisotropy and internal strain due to the lattice distortion at the ferroelectric domain walls. It is found that the piezomagnetism can lower the free energy of the system thus it favors the coupling between electric and magnetic domain walls. Due to the piezomagnetic effect, the clamped antiferromagnetic domain walls with spin orientation angle φ changing from 0 to π have different profiles comparing with those of φ changing from 0 to-π, and the former is energetically more favorable than the latter when the internal strain is tensile at the FEL domain walls while it is the contrary for compressive strain. Moreover, the strongest coupling between the FEL domain walls and the favorable AFM domain walls can be achieved at an optimized internal strain. © EDP Sciences, Societa Italiana di Fisica, Springer-Verlag 2010.link_to_subscribed_fulltex