Characteristics of LaAlO3 gate dielectrics on Si grown by metalorganic chemical vapor deposition

Abstract

Amorphous LaAlO3 (LAO) gate dielectric thin films have been deposited on Si substrates using La(dpm)3 and Al(acac)3 sources by low-pressure metalorganic chemical vapor deposition. The growth mechanism, interfacial structure, and electrical properties have been investigated by various techniques. The ultrathin films show smaller roughness of ∼0.3 nm, larger band gap of 6.47 eV, and good thermal stability. The growth follows a chemical dynamic control mechanism. High-resolution transmission electron microscopy confirms there exists no interfacial layer, or only thinner ones, between LAO and Si. X-ray photoelectron spectroscopy analyses reveal that the thinner interfacial layer is compositionally graded La–Al–Si–O silicate and Al element is deficient in the interfacial layer. The reliable value of equivalent oxide thickness around 1.2 nm of LAO/Si has been achieved.