X-ray imaging investigation of periodically electroded rubidium titanyl arsenate, RbTiOAsO4, under an applied electric field

Abstract

The behaviour of a (001) slice of initially single-domain rubidium titanyl arsenate (RbTiOAsO4, RTA) crystal, when prepared with a periodic Ag electrode of period 38 µm, as for periodic poling in nonlinear optics, is investigated for applied voltages of up to ±1.5 kV. The method of investigation is by synchrotron x-ray section topography with electric fields applied in situ, while under white-beam x-ray illumination at the ID19 topography beamline of the ESRF, Grenoble. An increasing expansion of the width of section topographs is observed with increasing voltage resulting from a corresponding bending of the lattice planes in the near-surface region, with angles ranging between 4–200 µrads. This behaviour is explained by the formation of a Schottky barrier, which results from a semiconductor–metal contact interaction between RTA and the Ag film, in the near-surface region beneath the high voltage electrode. This restricts the depth of the electric field to a near-surface depletion layer. The actual bending of the planes is by the electrostrictive strain that acts only in the depletion layer where the field is non-zero.