Grazing incident X-ray diffraction was observed from a thin silicon nano scale overlayer fabricated by oxidation and etch-back in a separation by implantation oxygen wafer at incident angles between 0.01o and 0.1o below the critical angle of total reflection (0.18o). We measured {220} reflections by probing the sample with respect to surface normal and found that the silicon nano scale overlayer has finite domains under strain close to the surface. We also found that annealing the sample up to 1000oC significantly reduced inhomogeneous strain and increased the size of the domains in the surface region of the silicon nano scale overlayer.
