UCL Discovery

Abstract

Oxide films of 3-7-nm thickness grown on both Si and SiGe at 400 °C in a dielectric barrier discharge source emitting 172 nm photons have exhibited excellent electrical properties - the leakage current densities of 1×10 A/cm being obtained at 1 MV/cm for the 3.0-nm thick oxide on SiGe and 3.4×10 A/cm for the 3.2-nm thick oxide on Si. A similar value of ∼5×10 A/cm at 1 V bias has been achieved for both oxides with thicknesses in the range of 5.5-7.0 nm. High dielectric strengths with hard breakdown values greater than 16 MV/cm were observed. The oxidations on both substrates has also demonstrated similarly good oxide and interface qualities, showing fixed oxide densities of ∼10 cm and midgap interface trap densities of ∼10 cm eV . The oxidation on SiGe was nearly twice as fast as that on Si, giving a growth rate of 0.6 Å/min. The active oxygen species (O and O ) generated by the 172 nm photon-induced reactions not only act as the oxidants but also assist in annihilating the oxygen vacancies and defects in the oxides to improve the leakage properties of the oxides. © 2003 Elsevier B.V. All rights reserved.