Electron Spin Resonance Study of Electron-Irradiated ZnS Crystals Containing Stacking Faults

Abstract

Three kinds of photosensitive ESR signals (V₁, V₂, F) have been found to be produced by electron irradiation. Signals V₁ and V₂ (V₁ having g_⁄⁄=2.0030, g_⊥=2.0550, and axial symmetry along the twinning [111]_w axis; V₂ having g_⁄⁄=2.0030, g_⊥=2.0530, and axial symmetry along another ⟨111⟩ axis) are ascribed to Zn vacancies (V centers) situated at stacking faults; V₁ is due to a hole localized on the S ion next to the Zn vacancy along the [111]_w axis; V₂ is due to a hole localized on one of the other three S ions next to the Zn vacancy. The signal F (g=2.0027 and isotropic) is ascribed to F centers. The excitation, quenching, and enhancing bands of the V centers are around 2.85 eV, 1.8 eV, and 1.3 eV, respectively. For F centers the excitation bands are around 3.4 eV and 1.8 eV, while the quenching bands are around 2.8 eV and 2.1 eV. A band model is proposed to interpret these photosensitivities.