Epitaxial praseodymium oxide: a new high- K dielectric

Abstract

We show results for molecular beam epitaxial growth of praseodymium oxide on Si. On Si(1 0 0) oriented surfaces, crystalline Pr 2O 3 grows as (1 1 0)-domains, with two orthogonal in-plane orientations. Epitaxial overgrowth with Si could not been realized so far. We obtain perfect epitaxial growth of hexagonal Pr 2O 3 on Si(1 1 1). These layers can also be overgrown epitaxially with Si leading to novel tunnel structures. Crystalline Pr 2O 3 on Si(0 0 1) is a promising candidate for highly scaled gate insulators, displaying sufficiently high- K value of around 30, ultra-low leakage current density, good reliability, and high electrical breakdown voltage. The Pr 2O 3/Si(0 0 1) interface exhibits the symmetric band alignment, desired for applying such material in both n- and p-type devices. The valence band as well as the conduction band offset to Si is above 1 eV. The electron masses can be assumed to be very heavy in the oxide. This effect together with the suitable band offsets leads to the unusually low leakage currents found experimentally. Finally, the integration of crystalline Pr 2O 3 high- K gate dielectrics into a conventional CMOS process will be demonstrated.