Sol-gel Method Doped With Er To (3 +): Al <sub> 2 </ Sub> O <sub> 3 </ Sub> Preparation And Property Research

The Er³+-doped Al₂O₃ waveguides are in period for applied basic research now. Little has been studied for the phase structure of Er³+-doped Al₂O₃, and the mechanism of luminescence for Er³+ in Al₂O₃ has not been understood. In this work, the Er³+-doped Al₂O₃ waveguides material was prepared by sol-gel method. The effects of Er³+ doping concentration and sintering temperature on optical properties have been obtained, in order to further study the mechanism of luminescence for Er³+-doped Al₂O₃. The 0-20 % Er³+-doped Al₂O₃ powders have been prepared by sol-gel method. A phase diagram for 0-20 % Er³+ doping concentrations is illustrated from 550 to 1250 ℃. The powders are single-phase γ-(Al,Er)₂O₃ sintered below 850 ℃, and the mixture of γ-(Al,Er)₂O₃ and θ-(Al,Er)₂O₃ phases at 900 ℃. The α-(Al,Er)₂O₃, Al10Er6O24 and ErAlO₃ phases are produced, following the higher temperature and Er³+ doping concentration. Er³+ doping makes them amorphous for γ-(Al,Er)₂O₃ and θ-(Al,Er)₂O₃ phases, and the tendency shows more evident with the increase of Er³+ doping concentration. Er³+ doping decreases the rate of the phase transformation for γ-(Al,Er)₂O₃→θ-(Al,Er)₂O₃ and θ-(Al,Er)₂O₃→α-(Al,Er)₂O₃, and the corresponding transformation temperature are increased by 10-20 ℃. For the 1 % Er³+-doped Al₂O₃ powders, the photoluminescence (PL) intensity increases with increasing sintering temperature. At the same sintering temperature of 900 ℃, the PL intensity has no change for 0.5 and 1 % Er³+-doped Al₂O₃ powders, and decreases with increasing Er³+ doping concentration above 1.5 % Er³+ doping concentration. The sintering temperature and Er³+ doping concentration have no influence on the curve shape of PL. The 0-1.5 % Er³+-doped Al₂O₃ waveguides films have been prepared on oxided Si substrate by the sol-gel method using the dip-coating process. The thickness of the Er³+-doped Al₂O₃ films for 9 layers is about 1.2 μm under a constant withdrawn rate (100 mm/min). The film surface is even, smooth and compact. The crystal size of the 0 % Er³+-doped Al₂O₃ film is very small, 30-50 nm, and increases to 100-300 nm at the 1.5 % Er³+-doped concentration. The PL spectra of Er³+ ions in the films were characterized in the infrared region from 1.43 to 1.67 μm. The evident peaks were observed at 1.534 μm measured at 10 K and 300 K. The full width at half maximum (FWHM) and intensity of PL decreases, with increasing Er3+ doping concentration. The Er3+-doped Al2O3 waveguides films have been prepared on SiO2 substrate by the sol-gel method using the dip-coating process. The experimental results indicated that the 1 % Er3+:γ-Al2O3 films, which have an face-centered-cubic structure with a (110) preferred orientation, were obtained at 900 ℃. The broadband peaks were observed at 1.534 μm measured at 300 K, and the full width at half maximum (FWHM) and intensity of PL decreases, with increasing pump powder.