Structural and magnetic properties of Si semiconductor co-implanted by Fe- and N-ions

Fe and N ions were co-implanted into Si wafers using the metal vapor vacuum arc technique and Kaufman technique. Structural analysis showed that Fe ions existed in the matrix at isolated substitution sites in the low dose sample (2.0 × 1016 cm−2), while in the high dose samples of 5.0 × 1016 cm−2 and 2.0 × 1017 cm−2, the non-ferromagnetic FeSi2 phase formed. The co-implanted samples with the high implanted doses of 5.0 × 1016 cm−2 and 2.0 × 1017 cm−2 showed room-temperature ferromagnetism. The saturated magnetization decreased with the increase of the implanted dose. Self-annealing can make for the formation of FeSi2 phase, which resulted in the observed decrease in the saturated magnetization. The origin of the ferromagnetism was from the substituted Fe ions randomly embedded in the Si matrix.