INFLUENCE OF THE SIZE EFFECT ON THE STRUCTURE AND OPTICAL PROPERTIES OF THIN GST FILMS IN AMORPHOUS AND CRYSTALLINE STATES

Abstract

The influence of the size effect on the structure and optical properties of thin amorphous and crystalline films based on the Ge₂Sb₂Te₅ phase memory material is studied. Films with a thickness of 50 to 300 nm were obtained by ion-plasma magnetron RF sputtering. Using Raman spectroscopy, it was found that the structure of amorphous and crystalline films does not depend on their thickness. In contrast, the study of the optical properties revealed that, as the film thickness increases, the fundamental absorption edge shifts to the long wavelength region of the spectrum. It was found that with an increase in the thickness of amorphous and crystalline films, a decrease in their optical band gap (E_g) is observed, and the main change in the value of E_g occurs in the thickness range from 50 to 100 nm and E_g of amorphous films is noticeably larger than that of crystalline films.