CRYSTAL-GROWTH OF SILICON FROM X-RAY EXCITED-STATES OF THE SOLID

Amorphous silicon films were irradiated on a water-cooled specimen holder by X-rays using synchrotron radiation. The irradiation effect was investigated by Raman spectroscopy and electron microscopy. It was found that the irradiation at room temperature greatly enhanced homogeneous nucleation in post-annealing at 600-degrees-C, whereas X-ray irradiation with a 54-pole wiggler heated the films up to about 500-degrees-C, and dislocation-free with a thickness of 300 nm were grown epitaxially within 10 min. When dose rates exceeded the growth threshold, the growth rate depended on dose rates and weakly on growth temperature. A growth rate of 10(-5) cm/s at 500-degrees-C was achieved by the X-ray irradiation which was 3 orders of magnitude higher than that of thermal solid-phase growth at the same temperature. Impurity segregation at the growth interface took place as observed in the melt growth. The irradiation effect is non-thermal and leads to crystal growth from an ''excited structure'' which is considered to have vacancies and self-interstitials at very high densities formed by inner-shell excitation of silicon.