Epitaxial, high-K dielectrics on silicon: the example of praseodymium oxide

We show the first results for crystalline growth of praseodymium oxide on Si as a potential high-K dielectric with very promising electrical properties. All layer growth experiments were performed using solid source molecular beam epitaxy. The initial growth phase was studied using scanning tunneling microscopy. On Si(0 0 1) oriented surfaces, crystalline Pr₂O₃ grows as (1 1 0)-domains, with two orthogonal in-plane orientations. Epitaxial silicon overgrowth seems to be impossible. We obtain perfect epitaxial growth on Si(1 1 1). These layers can also be overgrown epitaxially with silicon. Finally, we show that the structural quality of epitaxial grown Pr₂O₃ on Si(0 0 1) degrades when the film is exposed to air due to silicon oxide formation at the interface based on oxygen indiffusion. However, it can be stabilized by capping with Si.