Tuning of structural and dielectric properties of Gd2O3 grown on Si(001)

The structural and dielectric properties of gadolinium oxide (Gd 2O 3) grown on Si(001) depending on the epitaxial growth conditions were investigated. Gd 2O 3 layers were grown at temperatures between 250 mml:mspace width=".1em"mml:mspace degrees C and 400 mml:mspace width=".1em"mml:mspace degrees C with an oxygen partial pressure between 2 x 10 - 7 mml:mspace width=".1em"mml:mspace mbar and 5 x 10 - 7 mml:mspace width=".1em"mml:mspace mbar. The crystal structure of the Gd 2O 3 turns out to be monoclinic with rotational domains as revealed by x-ray diffraction measurements and transmission electron microscopy (TEM) investigations. The dielectric properties can be tuned with growth temperature, forming gas annealing, and an increase in oxygen partial pressure. Furthermore, the dielectric constant was found to increase with the layer thickness. This can be interpreted in terms of the presence of a two layer stack consisting an interfacial quasi-amorphous and monoclinic Gd 2O 3 on top, as confirmed by TEM. The value of around 33 was extracted for the dielectric constant of monoclinic Gd 2O 3, which is much higher than for cubic Gd 2O 3. The best Gd 2O 3 layers grown at 400 mml:mspace width=".1em"/mml:mspace> degrees C and p O 2 = 5 x 10 - 7 mml:mspace width=".1em"mml:mspace mbar exhibit also a characteristic leakage current value J ( V fb - 1 V ) for a CET value of around 2nm in the range of a few nA/cm 2, which enable the applicability in electronic devices.