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1.
Volk T. R. Bodnarchuk Ya. V. Gainutdinov R. V. Kokhanchik L. S. Shandarov S. M. 《JETP Letters》2021,113(12):769-779
JETP Letters - Studies of ferroelectric nano- and microdomain structures formed in LiNbO3-based optical waveguides are reviewed. Nanodomain structures of a given configuration have been written in... 相似文献
2.
L. S. Kokhanchik D. V. Irzhak V. V. Antipov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2008,2(4):546-552
Congruent lithium niobate crystals with periodic domain structures formed by the method of thermoelectric postgrowth treatment have been investigated. Periodic domain structures in the samples of polar ZY-, YZ-, and YX-cuts were characterized by scanning electron microscopy, high resolution x-ray diffractometry, and topography. The evaluation and comparison of the secondary electron (SE) signal cycling, electron emission coefficient, and charge value to equalize the differences in the SE signal have allowed us to specify the features of ZY-and YZ-cut structures. A correlation between the crystal lattice distortions near domain boundaries and the type of domain walls has been found. The domain walls separating the areas with the tail-to-tail P s vectors not only cause stronger crystal lattice distortions near them, but also are charged less quickly under electron irradiation. 相似文献
3.
Individual domains and domain gratings were fabricated on nonpolar Y-cuts of LiNbO3 and LiNbO3-Zn crystals by electron beam irradiation. The domains which nucleated in the irradiation points are frontally growing along the direction +Z within a thin (of about several microns) surface layer. The regularities of this motion are discussed in the framework of the approach to formation of space-charge fields under e-beam charging of insulators. The obtained dependency of the domain length on the exposure time permits us to propose the viscous-friction mechanism for the observed frontal domain growth. The velocity of the frontal growth in LiNbO3-Zn is higher than in LiNbO3 obviously due to a decreased number of pinning centers at the Nb-antisites. In LiNbO3-4 %Zn crystals planar domain gratings were fabricated by means of point-to-point irradiations along the X- and Z-directions with specified distances between the irradiation points. It is shown that the domain gratings are generated by a total field of point charges $ \vec{E} = \sum\nolimits_{i = 1}^{n} {\vec{E}_{i} } $ , where E i is the space-charge field induced in any irradiation point, and n is the number of points. Some preliminary estimates indicate that the frontal growth of domains under e-beam irradiation occurs at fields E < E c. 相似文献
4.
L. S. Kokhanchik M. V. Borodin S. M. Shandarov N. I. Burimov V. V. Shcherbina T. R. Volk 《Physics of the Solid State》2010,52(8):1722-1730
Regular domain structures on the Y cuts of the LiNbO3 substrates and Ti:LiNbO3 waveguide structures based on these substrates have been fabricated under electron-beam irradiation. It has been revealed
that the domains in undoped and titanium-doped LiNbO3 crystals are formed as a result of different processes. It has been demonstrated using chemical etching and waveguide second-harmonic
generation that regular domain structures in the Ti:LiNbO3 waveguides are formed at a depth of approximately 8 μm from the surface, where the titanium concentration does not exceed
2 mol %. The quasi-synchronous waveguide optical second harmonic generation with an efficiency of 8.8% has been obtained using
the fabricated structures. 相似文献
5.
L. S. Kokhanchik 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(4):402-405
An extraordinary potential contrast of a plane domain wall forming in the case of excess negative charging of a ferroelastic-ferroelectric Tb2(MoO4)3 sample with a two-domain structure has been detected using a scanning electron microscope. Conditions and features of the formation of this potential contrast (called charge contrast) in the domain wall region are determined. It is shown that the surface is charged at a lower rate in the domain wall region, which is an elastically strained crystal region. The smallest domain wall width determined by the charge-contrast image was 1.6 μm on the average. 相似文献
6.
7.
L. S. Kokhanchik M. N. Palatnikov O. B. Scherbina 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(5):740-746
The growth of a periodic domain structure in LiNbO3 crystals doped with gadolinium (Gd, 0.44 wt %) was investigated by special electron beam surface charging in a scanning electron
microscope and on a atomic force microscope. Ferroelectric domain boundaries with “tail-to-tail” and “head-to-head” P
s
orientations were comparatively analyzed. The domain boundaries had different forms and differed by their physical properties.
Micron-size surface crystal regions close to the “tail-to-tail” boundaries were charged slower by electron irradiation and
had modified elastic properties. This region was detected by using the lateral force mode of atomic force microscopy. The
observed morphology and property features were supposed to be due to different concentration gradients of the Gd impurity
and different width of its distribution close to the domain boundaries of different types. 相似文献
8.
The processes of the formation of domain structures in lithium tantalate crystals (≈300 μm thick) under electron irradiation
in a scanning electron microscope were studied. Successive discrete quasi-point irradiations with an electron beam over the
—Z-cut surface were used. This method of drawing by an electron beam made it possible to control the implanted charge and
to examine the influence of the distances between conditionally point charges on the domain structure formed during switching.
The effect of change in the direction of the beam displacement under irradiation on the domain-line width was investigated.
The domain lattice with a period of 12 μm was formed on the —z face of the crystal, which transformed into a 2D-type structure deep in the crystal. 相似文献
9.
L. S. Kokhanchik 《Physics of the Solid State》2018,60(9):1778-1785
Ferroelectric domain structures formed by an electron beam in lithium niobate crystals are studied using low-voltage SEM microscopy. The structures are formed in crystals with different conductivity, including samples with high-resistance congruent composition (CLN) and samples with conductivity increased by reductive annealing (RLN). The potential nature of the contrast of the domain structures observed in the secondary electron mode depending on the conductivity of the samples and the direction of spontaneous polarization of the domains is analyzed. It is assumed that the domain contrast in CLN crystals is associated with long-lived charges localized near domain walls and in the irradiated areas. The recorded domain structures in the CLN crystals are visualized on polar and nonpolar cuts. In the RLN crystals with improved conductivity compared to CLN, the potential contrast of the periodic domain structures is found only on the polar cuts, where vector Ps of the domains is perpendicular to the irradiated surface. This contrast is likely because the field of the spontaneous electric polarization charges influences the secondary electrons. 相似文献
10.
Using an electron beam, spontaneous polarization on the surface of +Z cuts of lithium niobate crystals of various compositions is switched. Domains 100–200 nm in size are formed in a thin surface layer, with the thickness dependent on the primary-electron energy. The sizes of segments, on which submicron domains are formed, exceed the sizes of the irradiation region. The distributions of domains on the surface in crystals of various compositions are different and depend on the method of moving the electron beam and irradiation conditions. The results are discussed in the context of notions on the charging of dielectric materials by the electron beam. It is assumed that the spontaneous polarization in the surface layer of +Z cuts of lithium niobates is switched by the field of a double layer of charges formed as a result of the charging process near the surface. 相似文献