INVESTIGATION OF HYDROGEN IMPLANTED LINBO3 CRYSTALS UNDER DC ELECTRIC-FIELD BY SYNCHROTRON-RADIATION TOPOGRAPHY

The results obtained by synchrotron radiation topography on lithium ni obate (LiNbO3) single crystals implanted by hydrogen are reported. Par ticular attention is paid to the influence of a DC electric held on th ese crystals. The section topographic experiments allow observation, c learly 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 proport ional to the field and appears to be strongly related to the piezoelec tric effect. Chemical etching and topographic experiments indicate tha t the observed layer corresponds to a region of inverse polarization w ith respect to the bulk, several microns thick, situated at the level of the implanted layer.