Paramagnetic Resonance Study of a Deep Donor in Silicon

Abstract

The impurity sulfur acts as a double donor in silicon. Assuming the ion to be substitutional, ${\mathrm{S}}^{+}$ is analogous to neutral phosphorus, except that the binding energy of the donor electron is much greater. Here we report paramagnetic resonance absorption of ${\mathrm{S}}^{+}$, including a detailed study, made using electron-nuclear-double-resonance techniques, of the hyperfine interaction with neighboring ${\mathrm{Si}}^{29}$ nuclei. We find hyperfine interaction constants which are inconsistent with the Kohn-Luttinger wave function (derived from the effectivemass approximation and intended for shallow donors) as applied to ${\mathrm{S}}^{+}$. This result indicates that contributions to the ${\mathrm{S}}^{+}$ donor wave function from parts of the silicon energy band structure (notably ${\ensuremath{\Delta}}_{{2}^{\ensuremath{'}}}$) other than the ${\ensuremath{\Delta}}_{1}$ conduction-band minima are important. Resonant absorption also is reported for other centers including a sulfur pair and several iron-sulfur pairs.