Surface Morphology Studies of Strained and Oxygen Deficient Epitaxial Thin films of Strontium Titanate and Calcium Manganese Oxide

Calcium Manganese Oxide (CMO) and Strontium Titanate (STO) are technologically important materials for applications. Our recent work on epitaxial thin films of CMO have shown that films with a tensile lattice mismatch strain exhibit structural and electrical properties that indicate oxygen deficiency. Our Atomic Force Microscopy studies of CMO thin films reveal time dependent surface morphological changes accompanying oxygenation and de-oxygenation of the CMO films. AFM images indicate possible ordering of oxygen vacancies on the surface. Currently we are extending these studies to epitaxial thin films of STO to investigate strain-oxygen stoichiometry coupling. We will report the results of our systematic studies of the evolution of surface morphology with changes in the strain state and oxygen stoichiometry