Fabrication of biaxially textured magnesium oxide thin films by ion-beam-assisted deposition

Biaxially textured MgO thin films were grown by ion-beam-assisted deposition. The film growth parameters of film thickness, ion-to-atom arrival ratio (r-value), ion beam angle, and ion beam voltage were studied. Film characterization was performed by X-ray diffraction, pole figure analysis, and atomic force microscopy (AFM). Full-width half-maximum (FWHM) of MgO (220) ϕ-scans and MgO (002) ω-scans, respectively, were used to evaluate in-plane and out-of-plane film texture. MgO (220) ϕ-scan FWHM of 3.2° and MgO (002) ω-scan FWHM of 1.2° was achieved on amorphous Si3N4-coated Si substrates using a 1500-V ion source oriented at 45° to the substrate normal and an r-value of 0.90. Depositions on metallic substrates yielded MgO (220) ϕ-scan FWHM values of 5.2° and MgO (002) ω-scan FWHM of 2.5°. Root-mean-square surface roughness of these films as measured by AFM was ≈2.3 nm.