Determining thickness and optical properties of a-SiOx thin films by PUMA and envelope method

Abstract

Abstract The gas-jet electron beam plasma chemical vapor deposition method was used for silicon suboxide (a-SiOx) thin films synthesis. According to the EDS data, stoichiometric coefficient of the films varied from 0.5 to 1.63 with changes in the flow rate of 5%SiH4+95%Ar gas mixture (R) from 89 to 18 sccm. Spectral transmittance, containing interference maxima and minima, was obtained in the range from 300 to 1000 nm. The refractive index and the thickness of a-SiOx thin films obtained from transmission spectra by the envelope method and PUMA were in good agreement with each other. The refractive index of the thin films at 650 nm increased from 1.6 to 3.1 and the film thickness changed from 500 to 1200 nm with an increase of R. The thickness values discrepancy for sample synthesized with R=18 sccm may be explained as the difficulty of using PUMA for systems with close refractive index of the film and the substrate.