STRIPE-SHAPED FACETED MORPHOLOGY AND DOMAIN-STRUCTURE OF EPITAXIAL CEO2(110) LAYERS ON SI(100) SUBSTRATES

The microscopic structure of epitaxially grown CeO2(110) layers on Si(100) substrates is investigated using high-resolution electron microscopic techniques. Surface morphology observations using high-resolution secondary electron microscopy indicate that the layer has a texture structure with stripes elongated in two directions perpendicular to each other. From cross-sectional high-resolution transmission electron microscopy (HRTEM) observations, it is found for the first time that the surface corresponding to these stripes has a triangular shape, which indicates that the surface consists of (111) facets. Plan view HRTEM observations verify that there are two kinds of domains, and that the crystallographic in-plane directions of the two domains are exactly perpendicular to each other. Stripes located in parallel to each other belong to a single-crystal domain. Grain boundaries are seen where domains having different in-plane direction get in touch together. Reflection high-energy electron diffraction with [110] azimuth shows split streaks, resulting in a mesh pattern, which directly verifies that the surface consists of a combination of (111) and (111BAR) facets.