Structure and thickness-dependent lattice parameters of ultrathin epitaxial Pr2O3 films on Si(001)

Abstract

Pr 2 O 3 grown heteroepitaxially on Si(001) is a promising candidate for applications as a high-k dielectric in future silicon-based microelectronics devices. The technologically important thickness range from 1to10nm has been investigated by synchrotron radiation-grazing incidence x-ray diffraction. The oxide film grows as cubic Pr2O3 phase with its (101) plane on the Si(001) substrate in form of two orthogonal rotation domains. Monitoring the evolution of the oxide unit-cell lattice parameters as a function of film thickness from 1to10nm, the transition from almost perfect pseudomorphism to bulk values is detected.

Reflection high-energy electron diffraction study of molecular beam epitaxy growth of Pr2O3 on Si(0 0 1)

“…This pressure was measured by an ion gauge near the substrate. Quadrupole mass spectroscopy showed the existence of 16 O and 32 O species when the source target was dissociated.…”

“…Although being a binary oxide, cubic Pr 2 O 3 contains 32 metal atoms and 48 oxygen atoms per unit cell arranged in a double-edge fluorite structure with one fourth of the oxygen sites vacant and regularly ordered [13]. Moreover, the existence of pure Pr 2 O 3 in the cubic Mn 2 O 3 structure is only reported in epitaxial films [10,16] offered by the International Centre for Diffraction Data. The pure cubic phase is probably not stable under standard conditions.…”

Synchrotron x-ray scattering study of thin epitaxial Pr2O3 films on Si(001)

“…Because of the pronounced chemical and structural differences between the crystalline oxide and the Si͑001͒ substrate, this system is also an interesting object for fundamental studies of heteroepitaxy. [9][10][11][12][13] Initial studies indicated crystalline Pr 2 O 3 grown on Si͑001͒ to be a promising candidate for scaled gate insulators. 14,15 The Pr 2 O 3 was found to grow as ͓101͔-oriented single crystal domains, with two orthogonal inplane orientations.…”

“…17 So far, Pr 2 O 3 in the cubic Mn 2 O 3 structure has been reported only for epitaxial films. 6,13 A unit cell of cubic Pr 2 O 3 contains 32 metal atoms and 48 oxygen atoms arranged in a double-edge fluorite structure with one-fourth of the oxygen sites vacant and regularly ordered. 17 Clean Si͑001͒ surfaces exhibit a two-domain ͑2 ϫ 1͒-reconstructed surface when the miscut is smaller than 2°.…”

Temperature dependence of thin films growth on Si(001) substrates by pulsed laser deposition

“…Epitaxial growth of high-k oxide on silicon is regarded as an effective solution to this challenging technological problem [8]. Up until now, many of the gate dielectric layers reported in the literature have been epitaxially grown on Si substrates using chemical vapor deposition (CVD), molecular beam epitaxy (MBE), electron beam evaporation [9][10][11]. Unfortunately, most of these oxides that have been epitaxially grown on Si(0 0 1) substrate are adopting the unfavorable orientation (such as ð1 1 0Þ Re2O3 kð0 0 1Þ Si Þ which may cause twinning and other defects [12].…”