Ferromagnetism and microstructure in Cr implanted p-type (100) silicon

The magnetic properties and microstructure of p-type Si (100) implanted with 1.0×1015 cm−2 of Cr ions at 200 keV have been investigated by a superconducting quantum interference device (SQUID) magnetometer, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The magnetic hysteresis loops and saturation magnetization of 0.67–0.75 emu/g in a wide temperature range are observed in the as-implanted sample. Annealing of the as-implanted sample modifies the microstructure and therefore weakens the magnetic exchange interaction. TEM observations show that the as-implanted silicon layer is amorphous. After annealing at temperature ≥800 ∘C, the SEM showed that the implanted profile layer became blurred and narrow, the ferromagnetism was weakened, which should have resulted from the re-crystallization of the implanted amorphous layer. These results were further compared with magnetic hysteresis observed in Mn-implanted silicon.