Electron-Spin-Resonance Studies in ZnS:Ge and ZnS:Si

Abstract

Photosensitive electron-spin-resonance signals due to ${\mathrm{Ge}}^{3+}$ and ${\mathrm{Si}}^{3+}$ in ZnS are observed. These signals are much enhanced under uv excitation and quickly decreased by irradiation of light of longer wavelengths. It is found that for ${\mathrm{Ge}}^{3+}$ in cubic ZnS, $g=2.0086\mathrm{}\pm 0.0003$ and $A=305\mathrm{}\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$; for ${\mathrm{Si}}^{3+}$ in cubic ZnS, $g=2.0047\mathrm{}\pm 0.0003$ and $A=654\mathrm{}\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. A molecular-orbital treatment of the unpaired-electron wave functions satisfactorily accounts for the sign and the order of magnitude of the observed $g$ values. The correlation of the photosensitivity of resonance signals with the luminescence observed in these samples is discussed.