X-ray study of step morphology on a cleaved MgO(100) surface

Using a surface sensitive X-ray scattering technique, we investigated the atomic-scale step structure on a cleaved MgO(100) single crystalline surface. We show that the fine structure of a crystal truncation rod (CTR) contains distinct step peaks at L = 0.33 and 0.50 reciprocal lattice units. The data analyzed by a recently developed 1D model indicate that the cleaved MgO surface has in-plane positional correlation lengths of about 2000 Å, ten times longer than that of out-of-plane correlation length. We find the presence of surface step structures of two and three atomic layer steps with nearly equal abundance. We estimate the average terrace sizes of $\text{105 × 79}\text{and}\text{200 × 157}\text{A}\text{̊}{}^2$ for the two and three layer steps, respectively.