Photoinduced Crystallization of Amorphous GeTe and Sb2Te3 Films by Laser Beams of Different Structures

Phase-change materials are widely employed in nanotechnology and microelectronics due to their ability to reversibly switch between amorphous and crystalline states, thereby altering their electrical and optical properties. The ternary compound Ge2Sb2Te5, the most studied and widely used phase-change material, consists of two binary tellurides, GeTe and Sb2Te3, each of which is itself a promising phase-change compound. This paper investigates the modification of thin amorphous GeTe and Sb2Te3 films by continuous-wave laser beams with different spatial structures, including Hermite–Gaussian modes HG00 and HG01, vector beams, and an optical vortex. The irradiated regions are analyzed based on brightness assessments of optical images and Raman spectroscopy, making it possible to conclude that beams with an annular intensity profile are promising for forming an optimal heating profile and achieving more uniform crystallization compared with HG00. For all beam types, laser-induced structural transformation significantly manifested in the Raman spectra, are accompanied by a pronounced change in optical contrast (reflectivity) for germanium telluride, whereas considerably smaller changes are abserved for antimony telluride.