Abstract
The structure of Ge2Sb2Te5 thin films doped with Bi has been studied using TEM, Raman spectroscopy, and Optical Transmission Spectroscopy. Thin films were obtained by direct current (DC) ion–plasma sputtering with thicknesses from 60 to 200 nm. TEM images revealed an amorphous film structure with bismuth nanocrystallites with a size of ∼1 to ∼20 nm. A shift in the Raman peaks of Bi–doped Ge2Sb2Te5 films compared to undoped samples was observed. A shift of the fundamental absorption edge to the long wavelength region of the spectrum along with an increase in the concentration of bismuth were detected in the optical transmission spectra of the films. A decrease in the optical band gap of bismuth-doped films was found. It has been shown that with increasing bismuth content in the films, their conductivity also increases. It has been found from studies of the current–voltage film characteristics reversible switching effect takes place.