Ce^3＋/Er^3＋/Bi^3＋ triply-doped yttrium aluminum garnet （YAG） is synthesized using co-precipitation method. The Bi^3＋ concentration-dependent near-infrared （NIR） emission behavior is systemically in- vestigated. The NIR emission of Er^3＋ ions at 1531 nm is enhanced threefold by the addition of 7 mol% Bi^3＋. Bi^3＋doping results in the formation of exciton in YAG and the variation in the local environment of the doped rare-earth ions. The enhancement in NIR luminescence is ascribed to the combined effects of the sensitization of exciton→Ce^3＋ →Er^3＋ and the Bi^3＋ doping-induced adjustment of the local environment for Ce^3＋ and Er^3＋ ions.
A novel composite ultraviolet(UV)/blue photodetector is proposed in this paper.Lateral ring-shaped PN junction is used to separate photogenerated carriers and inject the non-equilibrium excess carriers to the bulk,changing the bulk potential and shifting the threshold voltage of the metal-oxide-semiconductor field-effect transistor(MOSFET)as well as the drain current.Numerical simulation is carried out,and the simulation results show that the composite photodetector has the enhanced responsivity for UV/blue spectrum.It exhibits very high sensitivity to weak and especially ultra-weak light.A responsivity of 7000 A/W is obtained when the photodetector is illuminated under incident optical power of 0.01μW.As a result,this proposed combined photodetector has great potential for UV/blue and ultra-weak light applications.
