Hall effect, photoluminescence, infrared absorption, deep level transient spectroscopy, and Raman scattering were used to study property and defects of ZnO single crystal grown by a chemical vapor transport method. As-grown ZnO was n-type with a free electron density of 1016-1017/cm3. It had a slight increase after 900C annealing in O ambient. The deep-level transient spectroscopy measurements revealed four deep level defects with energy at 0.30, 0.50, 0.68 and 0.90eV in the as-grown ZnO sample, respectively. After the high temperature annealing, only the 0.5eV defect survive and had a concentration increase. photoluminescence results of the as-grown and annealed ZnO indicate that the well-known green emission disappeared after the annealing. The result suggested a correlation between the 0.68eV defect and the green photoluminescence peak. Results of P-doped ZnO were also compared with the undoped ZnO sample. The nature of the defects and their influence on the material property were considered.

Native Deep Level Defects in ZnO Single Crystal Grown by CVT Method. Zhao, Y., Zhang, F., Zhang, R., Dong, Z., Wei, X., Zeng, Y., Li, J.: Proceedings of the SPIE, 2007, 6841, 68410I