Thermopower and electrical resistivity of undoped and co-doped /spl beta/-FeSi2 single crystals and /spl beta/-FeSi2+x thin films

Thermopower and electrical resistivity have been investigated of /spl beta/-FeSi/sub 2/ single crystals and /spl beta/-FeSi/sub 2+x/ thin films in the temperature range from 40 K to 1200 K. The single crystals were grown by chemical transport reaction with source material of different purity and with a Si/Fe ratio between 1.5 and 2.5 to obtain crystals from the Fe-rich and Si-rich boundaries of the homogeneity range, respectively. The undoped and co-doped thin films have been prepared in the range -0.06