Optical diffraction from Ge$_2$Sb$_2$Te$_5$ fishnet metasurfaces

TL;DR

This paper demonstrates a simple optical diffraction method to analyze the structural quality and parameters of Ge$_2$Sb$_2$Te$_5$ metasurfaces, providing a quick assessment tool validated against SEM and AFM.

Contribution

It introduces an optical diffraction technique for evaluating metasurface structure, offering a rapid and accessible alternative to traditional microscopy methods.

Findings

Optical diffraction patterns reveal metasurface symmetry and lattice constants.

The optical method's accuracy is confirmed by SEM and AFM comparisons.

Bright Laue diffraction patterns can assess metasurface quality visually.

Abstract

We report the creation of Ge$_2$Sb$_2$Te$_5$ metasurfaces on sapphire substrates by the ablation method and the study of their structural properties by scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical diffraction. The main emphasis is on the optical technique, which boils down to obtaining bright Laue diffraction patterns on a screen, observing them with the naked eye, and analyzing the fine structure of diffraction reflections. It has been demonstrated that in one simple optical experiment it is possible to assess the quality of fabricated metasurfaces, determine the structure symmetry, and, moreover, determine the number of structural elements and lattice constants of the micron-sized metasurface. The accuracy of the optical technique is confirmed by comparison with the results of studies by SEM and AFM methods.