Plasma-enhanced atomic layer-deposited La₂O₃ ultra-thin films on Si and 6H–SiC: a comparative study

The rare earth La₂O₃ is always a material of interest and has a potential to replace SiO₂ in metal oxide semiconductor devices. In this context, we investigated the structural and electrical properties of La₂O₃ ultra-thin films grown by indigenously developed plasma-enhanced atomic layer deposition on Si and 6H–SiC substrates. The tris(cyclopentadienyl)lanthanum III precursor and O₂ plasma as an oxidant were used as starting materials. The deposited La₂O₃ ultra-thin films were characterized by means of X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, atomic force microscopy and X-ray diffraction. The growth rate of 0.5 ± 0.05 Ǻ per cycle was determined from optimized process parameters. The XPS and XRD results show the formation of lanthanum silicate on Si, while no formation of silicate was found on SiC. Leakage current densities of 9.58 × 10^–3 A/cm² and 2.07 A/cm² at a bias voltage of 1 V have been determined for the Au/Cr/La₂O₃/Si and Au/Cr/La₂O₃/SiC capacitors, respectively.