Structure and property of Ge/Si nanomultilayers prepared by magnetron sputtering

Ge/Si nanomultilayers were prepared using magnetron sputtering deposition and adjusting the growth conditions, such as the substrate temperature, sputtering pressure, sputtering power and annealing temperature. The surface topography and microstructure of the nanomultilayers were characterized by X-ray diffraction, Raman spectrometry and AFM. The favorable pressure of working gas was about 0.6 Pa in our experimental conditions. The surface of the as-deposited film is compact and smooth when the sputtering power is 2 W/cm2. The as-deposited film is amorphous at room temperature, however, the film is crystalline at the deposition temperature of 300 °C. When the annealing temperature is 500 °C, the Ge/Si nanomultilayers transform into GeSi alloy because the thermal annealing activates Ge/Si atomic interdiffusion. At the annealing temperature of 700 °C, the interdiffusion increases and the amount of Ge in the germanosilicide phase had been decreased compared to that of the sample annealed at 600 °C. In addition, Ge may have segregated from the germanosilicide and lead to the formation of Ge nanocrystals. For the sample annealed beyond 800 °C, the strong agglomeration and the formation of Ge nanocrystals are present.