A magnetron sputtering system modified to produce ternary films has been used to map large portions of the ternary phase diagram for the Si-Al-Sn system. The system is unconventional because the stoichiometries of the elements sputtered on the substrates vary linearly with position and in an orthogonal manner. Variations in the composition and structure vs. position were obtained by electron microprobe analysis and X-ray diffraction, respectively. We found that the amorphous range spans all compositions with over 60 at.% silicon. Compositions containing less than 50 at.% silicon were mixtures of the amorphous phase and Sn and/or Al. No intermetallic phases were observed. A ternary non-equilibrium 'phase diagram' showing the phases produced in the sputtered films was constructed. (C) 2003 Elsevier B.V. All rights reserved.