Characterization of electron-beam recorded microdomain patterns on the nonpolar surface of LiNbO3 crystal by nondestructive methods

Abstract

We report on characterization of the electron-beam fabricated planar domain gratings on the nonpolar (Y-) surface of LiNbO3 crystals performed with the use of AFM and confocal second harmonic generation (SHG) microscopy. The dependence of domain formation on the irradiation conditions was investigated. The relation of domain thicknesses to the electron penetration depth is experimentally proved. In particular, the possibility of controlling the thickness of planar domains by varying acceleration electron-beam voltages is demonstrated. The observed specificity of SHG is analyzed in the framework of the Kleinman-Boyd theory [G. D. Boyd and D. A. Kleinman, J. Appl. Phys. 39, 3597 (1968)] and Uesu approach [Kaneshiro et al., J. Appl. Phys. 104, 054112 (2008); Kaneshiro et al., J. Opt. Soc. Am. B 27, 888 (2010)] extended in our case to reflection geometry. The calculations performed predict the dependence of SHG conversion efficiency η on the domain thickness, which is in a qualitative agreement with the experiment. It is shown that planar domains on top of the nonpolar surface always enhance the value of η as compared with the bare surface.

Domain formation on the nonpolar lithium niobate surfaces under electron-beam irradiation: A review

“…These results provide a calibration curve, which permits one to specify T d by matching the accelerating voltage U. The validity of this approach was confirmed experimentally both in bulk crystals [8][9][10][11] and He-implanted optical waveguides on the nonpolar LiNbO 3 surfaces. 12 By analogy with the case of in-plane domain motion under AFM-tip voltages applied to the nonpolar crystal surfaces, 25 the EB-induced field decreases with the distance from the irradiation point, so the domain thickness T d is expected to lowered along the polar axis.…”

“…In the given paper, we summarize our recent results 4,7-13 on EBDW on the nonpolar LiNbO 3 surfaces. In addition to some above-mentioned practical aspects, the convenience of this EBDW geometry for experimental studies is due to the fact that the written domains are accessible for 3D characterization, 8 which permits us to discuss the mechanism of domain growth. Further, we describe the dependence of domain formation on irradiation conditions and some material characteristics.…”

Electron beam recording of microdomains on the nonpolar LiNbO3 crystal surface at different SEM accelerating voltages

“…In [13][14][15][16], electron beam recording of micro domains and microdomain gratings on nonpolar X and Y surfaces of LiTaO 3 and LiNbO 3 crystals and in Ti implanted planar waveguides on LiNbO 3 Y cuts was performed [14]. During local irradiation of the nonpolar crystal surface, domains nucleated in the irradiation region frontally grow along the polar axis Z in the surface layer of thickness of about several micrometers.…”

Computer Simulation of Structure and Dimensions of Oxygen-Octaadric Clusters in Lithium Niobate Crystal and the Dynamics of Their Development With Changes in Composition

“…Моделирование позволяет достаточно просто и наглядно исследовать строение кластеров, изменение величины дипольного момента (определяющего спонтанную поляризацию и сегнетоэлектрические свойства кристалла) при изменении характеристик и состава кластеров. [2,[4][5][6], прямое экспериментальное исследование структуры которых, особенно наноразмерных кластеров, исследование динамики их развития в зависимости от состава кристалла существенно затруднено. Кластеры, как и точечные дефекты катионной подрешетки, нарушают трансляционную инвариантность структуры без изменения общей симметрии элементарной ячейки.…”

“…Дефекты в виде кислородно-октаэдрических кластеров с различными примесными ионами дают фотохромный эффект и являются аккумуляторами кислорода, что существенно ухудшает оптическое качество кристалла. Кроме того, на дефектах локализуются электроны, что оказывает влияние на эффект фоторефракции [5][6][7].…”