Nanometer surface gratings on Si(100) characterized by x-ray scattering under grazing incidence and atomic force microscopy

During rapid melting and resolidification of As-implanted Si(100) by pulsed laser irradiation a periodic lateral grating has been created on the Si surface. Structure and perfection of the grating is investigated by specular and diffuse x-ray scattering under grazing incidence and exit angles. Using synchrotron radiation we find sharp, off-specular diffraction rods perpendicular to the sample surface. Their lateral separation is given by the periodicity of the grating (522±1 nm), which is nearly the same as the light wavelength (530 nm) used in laser annealing the samples. Intensity measurements along the diffraction rods are used to determine the detailed structure of the surface grating by fitting the experimental results with model calculations. A sinusoidal shape is found with an average amplitude of 6±1 nm. This structure is confirmed by atomic force microscopy studies. The x-ray method presented will be a unique tool also applicable in the case of buried lateral nanostructures which are not accessible by surface-sensitive techniques, e.g., scanning probe methods