Above room temperature ferromagnetism in Mn-ion implanted Si

Abstract

Above room temperature ferromagnetic behavior is achieved in Si through Mn ion implantation. Three-hundred-keV ${\mathrm{Mn}}^{+}$ ions were implanted to 0.1% and 0.8% peak atomic concentrations, yielding a saturation magnetization of $0.3\phantom{\rule{0.3em}{0ex}}\mathrm{emu}∕\mathrm{g}$ at $300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for the highest concentration as measured using a SQUID magnetometer. The saturation magnetization increased by $\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}$ after annealing at $800\phantom{\rule{0.2em}{0ex}}\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}$ for $5\phantom{\rule{0.3em}{0ex}}\mathrm{min}$. The Curie temperature for all samples was found to be greater than $400\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. A significant difference in the temperature-dependent remnant magnetization between the implanted p-type and n-type Si is observed, giving strong evidence that a Si-based diluted magnetic semiconductor can be achieved.