Giant magneto-resistance in p-n junction composed of β-FeSi2-Si

Fe-Si alloy system was investigated on the magneto-resistance (MR) effects in a temperature range between 77K-RT and in high fields up to 30 T. The samples were prepared by sputtering Fe(200 nm) on n-Si(1 0 0) surface and variously annealed up to β-FeSi2 are obtained. The MR effects were found small less than several %, negative at RT and positive at T = 77 K for Fe-rich samples. For a sample at the stoichiometric β-Fe-Si2 on n-Si as a p-n junction, we found a positive MR as large as 30% at RT in B = 30 T. The physical mechanism of the large MR is tentatively given by the carrier freeze-out effect in between the p-n.