Impact of fluorine admixture, hydrogen loading, and exposure to ArF excimer laser on photoluminescence of bismuth defects in amorphous silica

Photoluminescence (PL) excited by ArF (193 nm), KrF (248 nm) and N2 (337 nm) pulsed lasers is studied in bismuth doped unfused silicon dioxide synthesized on silica substrates by surface-plasma chemical vapor deposition (SPCVD). Additive free and fluorinated (F content ∼0.4 wt.%) amorphous silica are examined as host materials for bismuth. Three typical PL bands peaking at wavelengths of 650 nm (orange), 800 nm and 1400 nm (near infrared, NIR) were observed. It is found that fluorine additive weakly affects PL detail of as deposited samples. However, hydrogen loading completely deactivates NIR PL in the case of fluorine free sample, but only slightly suppresses the NIR band in fluorinated silicon dioxide. In fluorine free sample quenching of orange PL band caused by hydrogen loading is not as great as for the NIR band. By contrast, the NIR band intensity only slightly goes down in fluorinated silica sample, whereas the orange PL band becomes even more intense as a result of hydrogen loading. Exposure of the hydrogen loaded fluorine free sample to photons of ArF excimer laser renews NIR PL Storage of fluorine free hydrogen loaded sample in oxygen ambience leads to significant increase of the NIR PL band intensity. The effect of hydrogen loading is explained by collisional deactivation of the excited NIR PL centers. Subsequent outcome of H2 molecules accelerated by UV irradiation and/or storing the sample in oxygen ambience leads to PL recovery. Presence of fluorine in silica network somehow prevents NIR PL centers from collisions with interstitial hydrogen molecules. These molecules at the same time considerably neutralize the negative effect of fluorine on the intensity of the orange PL band. No impact of fluorine on either effectiveness of the orange PL band excitation via electron-hole recombination or inactivity of this process for the NIR PL band excitation is observed.