Transmittance enhancement of amorphous SiO2 via ultraviolet irradiation to eliminate atomic defects

Abstract

Optical absorption defects seriously degrade the performance of amorphous-SiO₂. Laser/UV conditioning (LC/UC) emerge as promising methods for defects elimination, yet its mechanism is still debated due to insufficient defect characterization methods. In this study, the experiments and machine learning potential were used to characterize the defects in Raman, phonon/vibrational density of states, and XRD spectra, the UC mechanism was implied. The UC transforms the atomic defects into medium-range order structure ($n$-fold rings) to reduce the absorption, the mobile oxygen O${}^0$ reduces the energy barrier in the reaction and shorter wavelength of UC is suggested. Experimental results validated that the absorption coefficient below 300 nm after 254 nm UC decreases 62% higher than that after 365 nm UC.