Investigation of hydrogen implanted LiNbO3 crystals under DC electric field by synchrotron radiation topography

The results obtained by synchrotron radiation topography on lithium niobate (LiNbO3) single crystals implanted by hydrogen are reported. Particular attention is paid to the influence of a DC electric field on these crystals. The section topographic experiments allow observation, clearly under an applied held and often without field application, of a layer associated with implantation, slightly misoriented with respect to the bulk. The misorientation of the image of this layer is proportional to the field and appears to be strongly related to the piezoelectric effect. Chemical etching and topographic experiments indicate that the observed layer corresponds to a region of inverse polarization with respect to the bulk, several microns thick, situated at the level of the implanted layer.