Spin Resonance of Transition Metals in Silicon

Abstract

Spin resonance measurements are reported for various charge states of four transition metals in silicon, namely for ${\mathrm{V}}^{++}$, ${\mathrm{Cr}}^{+}$, ${\mathrm{Mn}}^{\ensuremath{-}}$, ${\mathrm{Mn}}^{++}$, and ${\mathrm{Fe}}^{0}$. In each case the $g$ tensor and the hyperfine interaction with the impurity nucleus are isotropic. Thus each element exists in an isolated form in silicon and undergoes no distortion from the site of maximum symmetry. The site may be either the substitutional position or the interstitial position of maximum symmetry in the silicon lattice. For ${({\mathrm{V}}^{51})}^{++}$, $S=\frac{3}{2}$, $A=\ensuremath{-}42.10$; for ${({\mathrm{Cr}}^{53})}^{+}$, $S=\frac{5}{2}$, $a=+30.16$, $A=+10.67$; for ${({\mathrm{Mn}}^{55})}^{\ensuremath{-}}$, $S=1$, $A=\ensuremath{-}71.28$; for ${({\mathrm{Mn}}^{55})}^{++}$, $S=\frac{5}{2}$, $a=+19.88$, $A=\ensuremath{-}53.47$; for ${({\mathrm{Fe}}^{57})}^{0}$, $S=1$, $A=6.98$, where $a$ is the cubic field splitting parameter, $A$ is the hyperfine interaction of the isotope noted, and both are expressed in units of ${10}^{\ensuremath{-}4}$ ${\mathrm{cm}}^{\ensuremath{-}1}$. Electron-nuclear double resonance was used for accurate measurement of $A$ and for the determination of $S$. In the case of ${\mathrm{Fe}}^{0}$, the electron spin was checked by noting that the iron line splits into two fine structure components under uniaxial stress. Association of Cr, Mn, and Fe with acceptors in silicon has been observed, as well as another charge state of isolated Fe.