Crystallinity Control in Low-Temperature Growth of Poly-Crystalline Ge by Ion Beam Deposition

An ion beam sputtering process was used to grow polycrystalline Ge films at low temperatures (200-400 °C). The effect of transition metals (Sn, Al) and ion assisted beam was evaluated to enhance grain growth. It was found that the presence of the seed metals facilitates the grain growth even at low temperatures, below eutectic point. Modification of the microstructure was found impinging the growth of Ge films with a 100 eV ion assisted beam in the energy dose range 0-7 eV/atom. Ge layers deposited on Sn with ~4eV/atom doses had the largest grain size. X-ray diffraction (XRD) and Atomic Force Microscopy (AFM) were employed to characterize the film microstructure. The grown poly-Ge films were used to grow GaAs structures.