Influences of Substrate Temperature on Structure, Electrical and Optical Properties of Magnetron Sputtering Ge2Sb2Te5 Films

Abstract Using magnetron sputtering method the Ge 2 Sb 2 Te 5 films were deposited at different substrate temperatures (from room temperature to 300 °C) on Si substrate. The structure and the crystallization temperature of the films were determined by X-ray diffraction and Differential Scanning Calorimeter, respectively. The electrical resistance and the reflectivity of the films were measured with a four-point probe and ultraviolet photo-spectrometer, respectively. Based on the reflectivity of the films, it is found that the reflectivity contrasts of the Ge 2 Sb 2 Te 5 films at the wavelengths of 405 and 650 nm change with the substrate temperature. The films prepared at room temperature are amorphous, and crystalline (fcc) at 140 °C, and a little hexagonal (hex) structure comes forth at 300 °C. At 140 °C the phase separation may take place, and exhibits significant influence on the electrical and optical properties.