High quality, high-k gate dielectric: amorphous LaAlO₃ thin films grown on Si(100) without Si interfacial layer

Abstract

High-k dielectric amorphous LaAlO₃ thin films have been grown on n-type Si(100) substrates by laser molecular beam epitaxy. The interfacial characteristics of the LaAlO₃ films on Si were measured by high-resolution transmission electron micrography and X-ray photoemission spectroscopy. A sharp interface without a silica inter-layer between the LaAlO₃ film and Si substrate was observed. Atomic force microscopy measurements indicated that the root-mean-square surface roughness within a 2μm×2μm area of the LAO films was 0.12 nm. The flatband voltage and fixed charge density of the 8 nm thickness LaAlO₃ films were about 0.355 V and 1.8×10¹²/cm², respectively. The leakage currents of the LaAlO₃/Si(100) samples with different film thicknesses of 5, 8 and 12 nm were 0.45, 0.23 and 0.05 mA/cm², respectively, at a +1 V dc bias voltage. LaAlO₃ appears to be one of the most promising high dielectric constant materials for use in future ultra large scale integrated devices.