Hideo Omoto

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

The internal stress and microstructure of ZnO films were investigated as a function of carbon dioxide (CO2) gas flow ratio [CO2/(O2+CO2)] during sputter deposition. The internal stress of the ZnO films decreased with increasing CO2 gas flow ratio. The carbon concentration in the films deposited using CO2 gas increased by up to 4.0 at. %. Furthermore, the ZnO films deposited without CO2 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.

Electrical and Structural Properties of ZnO/Ag Multilayers Deposited by Magnetron Sputtering for Energy-Efficient Windows

The low-emissivity (low-e) coatings consisting of glass/ZnO/Ag were prepared and the microstructures of Ag thin films were investigated as a function of oxygen gas pressure during the ZnO underlayer deposition. It was found from X-ray diffraction measurement that the Ag thin films exhibited well-crystallization and (111)-preferred orientation when the ZnO underlayers were deposited in low oxygen gas pressure. Furthermore, glancing X-ray reflectivity measurement revealed that the surface roughness of Ag thin films decreased with decreasing oxygen gas pressure during the ZnO deposition. It can be said from these results that the highly crystallized and smooth Ag thin films grew on the ZnO thin films deposited in low oxygen gas pressure. Besides, it can be considered that the Ag thin films were heteroepitaxially grown using the smooth and highly crystallized ZnO underlayers which can be obtained under low oxygen gas pressure; as a result, the microstructures of Ag thin films should be improved.

Reactive Sputter Deposition of SiOxNy Films under Ar–CO2–N2 Atmosphere

Amorphous SiOxNy films were deposited by pulsed-dc reactive magnetron sputtering using a boron-doped Si target under Ar–CO2–N2 atmosphere. The refractive index (n) varied continuously between 1.54 and 2.0 with the CO2 flow ratio [CO2/(CO2+ N2)], maintaining a high transparency in the visible range. Furthermore, the variations in the cathode voltage and deposition rate revealed that the target surface was progressively oxidized with increasing CO2 flow ratio. Thus, the films deposited with the CO2 gas exhibited a gradual n shift and a high deposition rate as compared with that deposited with the O2 gas. On the other hand, these films had the typical composition and structure of SiOxNy films prepared by reactive sputtering. These results indicate that the CO2 gas is an effective reactive gas for controlling the n of the SiOxNy films.