X-RAY STANDING-WAVE AND ION-SCATTERING STUDIES ON AU-IMPLANTED LINBO3(0001) SINGLE-CRYSTALS

X-ray standing wave and combined Rutherford backscattering spectrometr y and channeling experiments have been performed on Au-implanted and a nnealed (0001)-oriented LiNbO3 single crystals, At an ion dose of simi lar or equal to 1 x 10(15) cm(-2) confined in a 117 nm thick (FWHM) la yer, resulting in a Au/Nb ratio of congruent to 5 x 10(-3), no signifi cant cluster formation has been observed. Most of the An atoms have be en found to lie on the c-axis of the LiNbO, structure. However, they d o not occupy a single lattice site. Rather they appear to be distribut ed over several sites on the [0001] atomic strings, which contain Nb, Li and structural vacancy sites, A small fraction (similar to ca. 20%) of the Au atoms appear to be displaced from the threefold symmetry ax is - most likely at tetrahedral sites. The possibility of this fractio n of Au atoms existing as small clusters like dimers or trimers cannot be ruled out. (C) 1998 Elsevier Science B.V.