Structural and optical properties of a‐SiO_x:H thin films deposited by the GJ EBP CVD method

In this work, hydrogenated amorphous silicon suboxide (a‐SiO_x:H) thin films have been prepared by gas‐jet electron beam plasma chemical vapor deposition method (GJ EBP CVD) at a substrate temperature 260 °C. The argon to monosilane ratio R = [Ar]/[SiH₄] was varied and the influence of the ratio R on the structural and optical properties was investigated. In this method, R affects an oxygen concentration in the film of the silicon suboxide. FTIR measurement showed a decrease of the oxygen concentration from 40.7 to 11% with increasing R. The analysis of FTIR spectra showed the containing a large number polysilane (Si–H₂)_n groups that suggest the material column structure. Optical transmission spectra were recorded to investigate the optical properties and thickness of the a‐SiO_x:H thin films. The maximum of the growth rate is 2 nm s⁻¹ at R = 80. The optical bandgap E_g was derived from Tauc plots. It was found that the increase in the oxygen concentration not only leads to the increase optical bandgap, but also to the decrease the refraction index.