Structural and microstructural analyses of crystalline Er2O3 high-k films grown on Si (0 0 1) by laser molecular beam epitaxy

Abstract

Erbium oxide (Er2O3) films are well regarded as being suited for high-k replacement of SiO2 in endeavors to further miniaturize and enhance the performance of microelectronics. Er2O3 films were deposited on Si (001) substrates by laser molecular beam epitaxy. The structures and microstructures of the films and the interfacial layers were characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results from the XRD and selected area electron diffractions of Er2O3 films with thicknesses of 30 and 100nm indicate that the films are polycrystalline, with dominant (111) textures of Er2O3 {111} // Si (001). Amorphous layers dotted with small ordered islands were observed and confirmed to be located at the interfaces between the films and the Si substrates with dark-field image and high-resolution TEM. High-resolution Z-contrast imaging, energy dispersive X-ray spectroscopy and energy-filtered imaging were applied to identify the compositions of the interfacial layers. The salient feature is that the layers consist primarily of Er and O, with a very small amount of Si. This kind of Er–O-based interface layer may play a very important role in the electrical and optical properties of the films.