Direct formation of /spl beta/-FeSi/sub 2/ on substrate in evacuated sealed ampoule

A simple preparation method of /spl beta/-FeSi/sub 2/ on substrate was proposed by the isothermal heat treatment in an evacuated and sealed ampoule. The mechanism of this reaction process was investigated using compacted Si powder or mixed powder of Fe and Si and sputtered Fe films on Si substrates or sapphire substrates. The compacted powder was encapsulated in an ampoule and separated from substrate with sputtered Fe film. It was found that vaporized Si from Si powder reacted with Fe film to form /spl epsiv/-FeSi, which, in turn, initiated the reaction with Si substrate to form /spl beta/-FeSi/sub 2/ film. Furthermore, it was found that vaporized Fe, derived from mixed powder of Fe and Si, promoted the formation of /spl beta/-FeSi/sub 2/ single phase on thermally oxidized Si substrate.