Chemical and structural characterization of barium hexaferrite films deposited on 6H-SiC with and without MgO/BaM interwoven layers

Abstract

High quality epitaxial barium hexaferrite (BaM) films with saturation magnetization of 4.3 kG, coercivity of 389 Oe, and FMR linewidth of 500 Oe, have been deposited by pulsed laser deposition on 6H-silicon carbide (SiC) single crystal substrates using an interwoven layer of magnesium oxide (MgO) and BaM of approximately 16 nm thick. This paper presents a chemical and structural study of the intermediate stages of BaM film growth on the interwoven layers compared to intermediate stages of BaM film growth directly on a SiC substrate. The purpose of these experiments is to understand the role of the interwoven layers and thus further improve the magnetic properties of BaM integrated with SiC substrates. X-ray photoelectron spectroscopy surface analysis and depth profiling shows that the interwoven layers effectively eliminate silicon diffusion into the bulk BaM film, and prevent the Fe diffusion which reduces Fe/Ba ratios in films deposited without the interwoven layers. By comparing the initial stages of film growth on the MgO/BaM interwoven layers with film deposited with the same number of BaM shots on a bare SiC substrate, scanning electron microscopy and atomic force microscopy results suggest that the MgO/BaM interwoven layers promote two-dimensional growth and improve the crystallographic texture of the BaM films, likely through relief of the lattice mismatch.