Investigating the effects of smoothness of interfaces on stability of probing nano-scale thin films by neutron reflectometry

TL;DR

This paper studies how the smoothness of interfaces in nano-scale thin films affects neutron reflectometry measurements and proposes a method to improve the reliability of SLD retrieval.

Contribution

It investigates the impact of smooth interfaces on the stability of the reference method in neutron reflectometry and introduces a new approach for more reliable SLD reconstruction.

Findings

Smooth interfaces influence reflectivity and phase measurements.

The proposed method enhances the stability of SLD retrieval.

Continuous scattering potential models better represent real sample interfaces.

Abstract

Most of the reflectometry methods which are used for determining the phase of complex reflection coefficient such as reference method and Variation of Surroundings medium are based on solving the Schr\"odinger equation using a discontinuous and step-like scattering optical potential. However, during the deposition process for making a real sample the two adjacent layers are mixed together and the interface would not be discontinuous and sharp. The smearing of adjacent layers at the interface (smoothness of interface), would affect the reflectivity, phase of reflection coefficient and reconstruction of the scattering length density (SLD) of the sample. In this paper, we have investigated the stability of reference method in the presence of smooth interfaces. The smoothness of interfaces is considered by using a continuous function scattering potential. We have also proposed a method to achieve the most reliable output result while retrieving the SLD of the sample.