Photoluminescence of Intrinsie Defects in Glassy GeO₂. Twofold Coordinated Ge and Nonbridging Oxygen

Photoluminescence (PL) bands at 4.1 eV with decay time τ < 20 ns and at 3.0 eV with τ = 78 μs are excited in the oxygen defieiency‐related optical absorption band at 5.06 eV. These PL bands are closely similar to the PL bands in Ge‐doped glassy SiO₂. They are attributed to the transitions from ¹B₁ and ³B₁ excited states of a twofold coordinated Ge atom (Ge 20 center). In reaction with atomic hydrogen this PL center converts to the well‐known paramagnetic “H(II)” center charcterized by hydrogen hfs of 12.0 mT. γ‐irradiation of glass GeO₂ induces a PL band at 1.84 eV with τ = 4.6 μs, which similarly as in glassy SiO₂ is ascribed to the non‐bridging oxygen hole centers.