Influence of the growth temperature on the spectral dependence of the optical functions associated with thin silicon films grown by ultra-high-vacuum evaporation on optical quality fused quartz substrates

摘要

Following up on some recent work that has been presented (Orapunt et al., J Appl Phys 119:065702-1-12, 2016), we report on the optical properties associated with a unique form of thin-film silicon that has been deposited onto optical quality fused quartz substrates through ultra-high-vacuum evaporation. For the purposes of this particular analysis, we focus on how the growth temperature influences the spectral dependence of the optical functions associated with these thin silicon films, for growth temperatures ranging from 98 to 572 °C. Through measurements of the specular reflectance spectrum at near normal incidence and the regular transmittance spectrum at normal incidence, we determine the spectral dependence of the refractive index, the extinction coefficient, the real and imaginary parts of the dielectric function, and the optical absorption coefficient for the 11 thin silicon films considered in this analysis. We find that generally the refractive index increases in response to increases in the growth temperature. The optical absorption spectral dependence is also observed to exhibit a fundamental transition in its functional behavior accompanying increases in the growth temperature. Some details, related to recently developed methods employed for the determination of the optical functions from measurements of the reflectance and transmittance spectra, are provided as a complement to this analysis.