Internal Stress and Microstructure of Zinc Oxide Films Sputter-Deposited with Carbon Dioxide Gas

摘要

The internal stress and microstructure of ZnO films were investigated as a function of carbon dioxide (CO_2) gas flow ratio [CO_2/(O_2 + CO_2)] during sputter deposition. The internal stress of the ZnO films decreased with increasing CO_2 gas flow ratio. The carbon concentration in the films deposited using CO_2 gas increased by up to 4.0 at. %. Furthermore, the ZnO films deposited without CO_2 gas exhibited a preferred orientation of (002); however, the C-doped ZnO films exhibited random orientations. These findings suggest that the C atoms incorporated in the ZnO crystal lattice induce this random orientation, thereby relaxing the internal stress of C-doped ZnO films.