摘要
The effects of annealing on the chemical states of N dopant, electrical, and optical properties of N-doped ZnO film grown by molecular beam epitaxy （MBE） are investigated. Both the as-grown ZnO：N film and the film annealed in N2 are of n-type conductivity, whereas the conductivity converts into p-type conductivity for the film annealed in O2. We suggest that the transformation of conductivity is ascribed to the change in ratio of the N molecular number on O site （N2）o to the N atom number on O site （No） in ZnO：N films under the various annealed atmosphere. For the ZnO：N film annealed in N2, the percentage content of （N2）o is larger than that of No, i.e. the ratio 〉 1, resulting in the n-type conductivity. However, in the case of the ZnO：N film annealed in 02, the percentage content of （N2）o is fewer than that of No, i.e., the ratio 〈 1, giving rise to the p-type conductivity. There is an obvious difference between low-temperature （80 K） PL spectra of ZnO：N film annealed in N2 and that of ZnO：N film annealed in 02. An emission band located at 3.358 eV is observed in the spectra of the ZnO：N film after annealed in N2, this emission band is due to donor-bound exciton （D^0X）. After annealed in 02, the PL of the donor-bound exciton disappeared, an emission band located at 3.348 eV is observed, this emission band is assigned to acceptor-bound exciton （A^0X）.
The effects of annealing on the chemical states of N dopant, electrical, and optical properties of N-doped ZnO film grown by molecular beam epitaxy （MBE） are investigated. Both the as-grown ZnO：N film and the film annealed in N2 are of n-type conductivity, whereas the conductivity converts into p-type conductivity for the film annealed in O2. We suggest that the transformation of conductivity is ascribed to the change in ratio of the N molecular number on O site （N2）o to the N atom number on O site （No） in ZnO：N films under the various annealed atmosphere. For the ZnO：N film annealed in N2, the percentage content of （N2）o is larger than that of No, i.e. the ratio 〉 1, resulting in the n-type conductivity. However, in the case of the ZnO：N film annealed in 02, the percentage content of （N2）o is fewer than that of No, i.e., the ratio 〈 1, giving rise to the p-type conductivity. There is an obvious difference between low-temperature （80 K） PL spectra of ZnO：N film annealed in N2 and that of ZnO：N film annealed in 02. An emission band located at 3.358 eV is observed in the spectra of the ZnO：N film after annealed in N2, this emission band is due to donor-bound exciton （D^0X）. After annealed in 02, the PL of the donor-bound exciton disappeared, an emission band located at 3.348 eV is observed, this emission band is assigned to acceptor-bound exciton （A^0X）.
基金
Supported by the Hundred Talents Programme of Chinese Academy Sciences, the Key Project of the National Natural Science Foundation of China under Grant No 60336020 and 50532050, and Outstanding Overseas Chinese Young Scholar Foundation under Grant No 60429403, and the Direct Allocation Grant of Research Committee of Hong Kong under Grant No DAG04/05.SC24.
