Optical Spectroscopy Characterization of Se‐doped Bi12SiO20 Crystals

Crystals of Bi12SiO20 doped with Se (BSO:Se) are grown by the Czochralski method. The measured concentration of Se is 1.75×1018 N/cm−3 and an additional increase of the Fe concentration from 1.9×1018 N/cm−3 (undoped Bi12SiO20) to 6.4×1018 N/cm−3 (BSO:Se) is also detected. The lattice parameter of BSO:Se is 10.096 A. It is assumed that the doping takes place in the tetrahedral positions by replacement of 3Si4+ ions by (Se6++2Fe3+) ions. The doping is found to cause an increase of the absorption coefficient practically in the entire spectral interval (1.4–3.1 eV) studied by optical absorption spectroscopy. Such an effect is typical for all Fe‐doped Bi12SiO20 crystals. The weak bands situated in the 1.4–2.1 eV spectral range should be attributed to crystal‐field induced transitions of Fe3+ as well as of other uncontrolled impurities as Cr4+, Ni2+ and Co2+.