Er-166 atoms were implanted with an energy of 70 to 90 keV and doses of 0.8 to 2.0 X 10(17)/cm(2) into Si(111) substrates at temperatures ranging from 450 to 530 degrees C. We found that using conventional nonchanneled implantation at energies of similar to 90 keV, it is impossible to form a continuous ErSi1.7 layer. At best, after annealing, a discontinuous ErSi1.7 layer with poor crystalline quality (chi(min) = 40%) is obtained. On the contrary, using channeled implantation, a continuous epitaxial ErSi1.7 layer with very good crystalline quality can be formed; a lowest chi(min) value of 1.5% for a surface ErSi1.7 layer has been obtained. The origin of this different behavior is explained. Our results show that for synthesizing continuous ErSi1.7 layers with good quality using ion beam synthesis at energies around 90 keV, channeled implantation is indispensable. (C) 1995 American Institute of Physics.