Buried hexagonal AlB2-type YSi2 layers were formed by metal vapor vacuum arc implantation of 100 keV yttrium ions to a dose of 1 X 10(18) Y+, cm(-2) into p-type Si (1 1 1) wafers. The heterostructures were analyzed by X-ray diffraction (XRD), Rutherford backscattering spectrometry (RBS), Fourier transform infrared (FTIR) transmittance spectroscopy and the four-point probe technique. The results of XRD and RBS showed that YSi2 was formed directly during the implantation, and the implanted region from the surface to the interior of the Si substrate could be divided into four layers based on the concentration profile. The preferred growth was observed after infrared radiation. In situ measurements of sheet resistance during infrared irradiation showed that the as-implanted sample is metastable and the stable structure can be formed after irradiation at 530degreesC. Characteristic phonon bands Of YSi2-x silicides have been observed by FTIR spectroscopy. (C) 2002 Published by Elsevier Science B.V.