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 O-2 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 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 9.58x10(-3) A/cm(2) and 2.07 A/cm(2) at a bias voltage of 1 V have been determined for the Au/Cr/La2O3/Si and Au/Cr/La2O3/SiC capacitors, respectively.