Refractive index of nanoscale thickness films measured by Brewster refractometry

TL;DR

This paper demonstrates that Brewster angle refractometry can be used for precise measurement of nanoscale film refractive indices, highlighting challenges like surface scattering and the transition from 3D to 2D structures.

Contribution

It introduces a method for measuring nanoscale film RI using Brewster refractometry and discusses the effects of surface scattering and film thickness on measurement accuracy.

Findings

Refractive index measurements are feasible for nanoscale films.

Surface scattering affects measurement accuracy.

No significant RI change detected during 3D-2D transition.

Abstract

It is shown that reflective laser refractometery at Brewster angle can be usefull for precision measurements of refractive indexes (RI) in the transparency band of various films of nanoscale thickness. The RI measurements of nanoscale porous film on the basis of gadolinium orthosilicate and quartz have been carried out as first experience. It is shown that surface light scattering in such films that is connected with clustering of nanoscale pores can decrease the accuracy of the RI measurements at Brewster angle. Estimated physical dependence RI stipulated by the film thickness reduction (3D-2D transition) in the range of (20-160)nm has not been not detected.