Towards understanding epitaxial growth of alternative high-K dielectrics on Si(001): Application to praseodymium oxide

Abstract

First investigations demonstrate that crystalline Pr2O3 on Si(001) is a promising candidate for highly scaled gate insulators, displaying a sufficiently high-K value of around 30, ultralow leakage current density, good reliability, and high electrical breakdown voltage. Here, we report on molecular beam epitaxial growth of crystalline praseodymium oxide (as Pr2O3 in the bixbyite or manganese oxide structure) on Si(001) substrates. The Pr2O3 was found to grow as (110)-single-crystalline domains, with two orthogonal in-plane orientations. Investigations of the initial growth phase indicate that the occurrence of these domains is due to the nucleation on neighboring terraces with Si dimer rows (2×1 reconstruction) perpendicular to each other. We postulate the formation of a layer consisting of very small Pr2O3 islands on top of the Si dimers in the initial stage of growth. This interface layer acts as a coincidence lattice on which further growth in the (110) orientation can occur. X-ray photoelectron spectroscopy investigations indicate that the formation of the interface layer is accompanied by oxygen accumulation in the interface.