Epitaxial Ge2Sb2Te5 films on Si(111) prepared by pulsed laser deposition

Epitaxial Ge2Sb2Te5 (GST) thin films were successfully grown on Si(111) using pulsed laser deposition (PLD) at various substrate temperatures and pulsed laser beam frequencies. The films were characterized by X-ray diffraction regarding crystallinity, phase composition and texture. The films possess a hexagonal structure with a GST(0001) out-of-plane orientation. With increasing substrate temperature, the deposition rate decreases due to severe surface desorption during deposition as determined by X-ray reflectivity measurements. The deposition window for epitaxial growth ranges from 110° to 300 °C. The topography of the films shows triangularly shaped crystallites and the RMS roughness is typically around 0.6 nm for the films deposited between 200 °C and 250 °C. Single crystalline GST films could be synthesized with deposition rates of as high as 42 nm/min by varying the laser repetition frequency.