Specific features of ir photoluminescence of bismuth-doped silicon dioxide synthesized by plasmachemical method

Photoluminescence spectra and kinetics of the bismuth-doped silicon dioxide are studied in the wavelength interval 0.7-1.6 mu m in the absence and in the presence of aluminum co-doping. It is demonstrated that a broad spectral band that is centered at 1420 nm and exhibits a decay time of 600 mu s dominates in the long-wavelength part of the spectral interval regardless of the presence of aluminum in the directly deposited unfused bismuth-doped silicon dioxide. The melting of the plasma-deposited aluminosilicate material leads to the shift of the center of the band to a wavelength of 1100 nm, whereas the melting of the aluminum-free material weakly affects the spectrum. It is demonstrated that an increase in the temperature to 700 K causes an increase in the intensity of the band centered at a wavelength of 1420 nm, which is most clearly seen under the excitation at a wavelength of 808 nm. An increase in the intensity is accompanied by an increase in the lifetime and a sharp decrease in the intensity of the band peaked at a wavelength of 825 nm. The spectral features and kinetics of photoluminescence are interpreted in the framework of the three-level scheme of electronic transitions for two types of bismuth defects that simultaneously exist in the aluminosilicate materials and exhibit close energies of the stationary electronic states.