Room temperature deposition of GeO_2 thin film using dielectric barrier discharge driven excimer lamps

摘要

We discuss the fabrication of GeO_2 and GeO_2/SiO_2 films at room temperature by photo-chemical vapor deposition. Excimer lamps were used for the light source, and tetraethoxyorthogermanate (TEOG) and tetraethoxyorthosilicate (TEOS), as raw materials. First, we fabricated GeO_2 films from single-precursor TEOG. The surface of the films obtained with Ar_2~*, Kr_2~*, and Xe_2~* lamps was extremely smooth (R_(rms)～0.3 nm). Second, we fabricated GeO_2/SiO_2 composite films from a mixed vapor of TEOS and TEOG. In this instance, we used a Xe_2~* lamp, which was able to produce films of good quality for both SiO_2 and GeO_2 individually. The refractive indices of the obtained films showed intermediate values between those of SiO_2 (n =1.46) and GeO_2 (n =1.60). The relationship between the Ge concentration in these films and the refractive indices was examined. We successfully obtained a GeO_2/SiO_2 composite material of higher refractive index than that of similar composites produced by conventional methods.