engleski

Grazing incidence small angle x-ray scattering study of irradiation induced defects in monocrystalline silicon

Structural defects in monocrystalline silicon samples, irradiated with a dose of 2E16 He ions per square centimetre at 77K and annealed at temperatures in 100 - 800 oC temperature range, were investigated using grazing incidence small angle X-ray scattering Apart from the scattering intensity shape typical for this surface roughness, all the samples showed fringes in scattering intensity from the topmost, implantation unaffected layer. Apart from the step-down from nonimplanted to implanted sample, the critical angle is slowly decreasing with the annealing temperature increasing up to 600oC, when it starts to rise again. This results from redistribution of defects, and is indicating bubbles formation onset. Some of the induced defects are lost due to the diffusion towards the surface. This increases surface roughness, and causes the sample density to rise slowly and is detected as lowering of intensity of the reflected primary beam and the change of the shape of reflection. It is believed that the bubbles start to form at 600oC, and this is the temperature at which film thickness and the change in critical angle reverse their dependence on temperature of annealing..

silicon; helium; ion implantation; SAXS

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