Optical properties of electron beam evaporated Ge2Sb2Te5 thin films for rewritable high density data storage applications

Ge2Sb2Te5 thin films were deposited by electron beam evaporation onto glass substrates at 303 K and 453 K substrate temperatures. The effect of film microstructure (modified by substrate temperature) on optical properties over the visible region was analyzed. It is observed that Ge2Sb2Te5 thin films show good optical contrast in the lower wavelength region. Microstructural and spectral dependence on optical constants (n & k) of the films were studied. The optical band gap and the nature of transition of the Ge2Sb2Te5 thin films also have been reported. Amorphous to crystalline microstructural phase change due to substrate temperature in these films was confirmed by X-ray diffraction and SEM analysis.