Cathodoluminescence microcharacterization of the defect structure of quartz

Cathodoluminescence (CL) spectroscopy has been used to investigate the irradiation-sensitive defect structure of ultrapure synthetic quartz at 295 and 80 K. CL emissions are identified with particular defect centers. Insight into the processes of defect formation and subsequent electromigration resulting from the trapped-charge-induced electric field following irradiation by a stationary continuous electron beam are presented. The CL emissions are associated with either a nonbridging oxygen hole center (NBOHC) or trapped-electron Si₃^- center (1.91 eV); NBOHC with OH precursor (1.95 eV); the radiative recombination of the self-trapped exciton (STE) in irradiation-induced amorphous SiO₂ outgrowths (2.28 eV); an extrinsic process (2.46 eV); the radiative recombination of the STE associated with the E₁^' center in {α}-SiO₂ (2.72 eV); an additional component at 80 K due to the radiative recombination of the STE associated with the E₂^' center (2.69 eV); an intrinsic process (2.95 eV); and the charge-compensated substitutional aluminum center (3.12 eV).