Isoelectronic As doping effects on the optical characteristics of GaN films grown by metalorganic chemical-vapor deposition

We have studied the As doping effects on the optical characteristics of GaN films by time-integrated photoluminescence and time-resolved photoluminesc ence. When As is incorporated into the film, the localized defect levels an d donor-acceptor pair transition become less resolved. The recombination li fetime of neutral-donor-bound exciton (I-2) transition in undoped GaN incre ases with temperature as T-1.5. However, the I-2 recombination lifetime in As-doped GaN first decreases exponentially from 98 to 41 ps between 12 and 75 K, then increases gradually to 72 ps at 250 K. Such a difference is rela ted to the isoelectronic As impurities in GaN, which generate nearby shallo w levels that dominate the recombination process. (C) 2000 American Institu te of Physics. [S0003-6951(00)01941-0].