Ultrathin IBAD MgO films for epitaxial growth on amorphous substrates and sub-50 nm membranes

Abstract

A fabrication process has been developed for high energy ion beam assisted deposition (IBAD) biaxial texturing of ultrathin (∼1 nm) MgO films, using a high ion-to-atom ratio and post-deposition annealing instead of a homoepitaxial MgO layer. These films serve as the seed layer for epitaxial growth of materials on amorphous substrates such as electron/X-ray transparent membranes or nanocalorimetry devices. Stress measurements and atomic force microscopy of the MgO films reveal decreased stress and surface roughness, while X-ray diffraction of epitaxial overlayers demonstrates the improved crystal quality of films grown epitaxially on IBAD MgO. The process simplifies the synthesis of IBAD MgO, fundamentally solves the "wrinkle" issue induced by the homoepitaxial layer on sub-50 nm membranes, and enables studies of epitaxial materials in electron/X-ray transmission and nanocalorimetry.