Abstract

Preparation of quartz (rock crystal) films has been studied by an atmospheric pressure chemical vapor deposition method using Si(OC₂H₅)₄ and O₂ as starting materials in the presence of gaseous HCl. The films were deposited onto a sapphire (0001) substrate at 600–850 °C with a growth rate of 0.3–3.0 µm h⁻¹. Their X-ray diffraction profiles showed an intense diffraction peak at 50.6° assigned to the (0003) diffraction of quartz with a hexagonal structure suggesting epitaxial growth. The full-width at half-maximum was 10.0 min for the quartz film prepared at 850 °C. Reflection high-energy electron diffraction measurements showed a diffraction pattern similar to that of a single crystal of quartz. It was found by energy-dispersive analysis of the X-rays that the [O]/[S] ratios of the deposited films were in the range of 1.94–1.97, independent of the growth temperature. Fourier transform infrared spectra exhibited a weak absorption band at 3585 cm⁻¹, suggesting OH radicals to be present as an impurity. The refractive index of the quartz epitaxial films prepared at 850 °C was 1.528.