High-temperature induced nano-crystal formation in ion beam-induced amorphous sili-con ripples

We report on in-situ investigations of a recrystallization process of an ion beam-induced rip-pled silicon. The one dimensional ripple structure was created by 40Ar+ ion irradiation with dose of ~5x1017 ions/cm2 under an angle 60° with respect to the surface normal at an energy of 60 keV. At the surface the induced ripples have a period and an amplitude of about 915nm and 80nm, respectively. Structure and morphology of ripples were studied by two x-ray grazing in-cidence scattering methods, transmission electron microscopy and atomic force microscopy. X-ray grazing-incidence amorphous scattering pattern were recorded in-situ in a range from 250°C to 750°C. Up to about 500°C mainly we found a single broad scattering maximum cor-responding to the Si(111) inter-planar distances. At higher temperature these peaks becomes sharp and intense indicating the onset of a re-crystallization process in the amorphous top layer.
Two processes were found, a formation of crystalline islands at the top of amorphous surface ripples and a growth of polycrystalline twins close to the former amorphous-crystalline inter-face.