The magnetic/nonmagnetic p-n junction was prepared by implanting gadolinium into the n-type silicon with low-energy dual-ion-beam epitaxy technology.The magnet ic layer GdxSi1-x shows excellent magnetic properties at r oom temperature. High magnetic moment 10μB per Gd atom is observed, which is interpreted by RKKY mechanism. Magnetic/nonmagnetic p-n junctions show rectifying behaviour, but no magnetoresistance is observed.