Epitaxial growth of stoichiometric SiC on Si(111) and 2°–5° off-oriented 6H–SiC(0001) substrates was carried out at low temperatures (800–1000 °C) by means of solid-source molecular beam epitaxy controlled by a quadrupole mass spectrometry based flux meter. The films were obtained on Si-stabilized surfaces showing (3×3) and (2×2) superstructures in the case of SiC(0001). The reflection high-energy diffraction (RHEED) patterns and damped RHEED-oscillations during the growth on 6H–SiC(0001) at T≳900 °C indicate that two-dimensional nucleation on terraces is the dominant growth process.

The ability to integrate crystalline metal oxide dielectric barrier layers into silicon structures can open the way for a variety of novel applications which enhances the functionality and flexibility ranging from high‐K replacements in future MOS devices to oxide/silicon/oxide heterostructures for nanoelectronic application in quantum‐effect devices. We present results for crystalline gadolinium oxides on silicon in the cubic bixbyite structure grown by solid source molecular beam epitaxy. Additional oxygen supply during growth improves the dielectric properties significantly. Experimental results for Gd2O3‐based MOS capacitors grown under optimized conditions show that these layers are excellent candidates for application as very thin high‐K materials replacing SiO2 in future MOS devices. Epitaxial growth of lanthanide oxides on silicon without any interfacial layer has the advantage of enabling defined interfaces engineering. We will show that the electrical properties of epitaxial Gd2O3 thin films on Si substrates can further be improved significantly by an atomic control of interfacial structures. Finally, we will present a new approach for nanostructure formation which is based on solid‐phase epitaxy of the Si quantum‐well combined with simultaneous vapor‐phase epitaxy of the insulator on top of the quantum‐well. Ultra‐thin single‐crystalline Si buried in a single‐crystalline insulator matrix with sharp interfaces was obtained by this approach on Si(111). In addition, structures consisting of a single‐crystalline oxide layer with embedded Si nanoclusters for memory applications will also be demonstrated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The Si/dielectric interface properties influence device performance significantly. Often the interface is not stable and changes during and/or after the growth. For a better understanding of the interface and layer formation processes of Nd2O3 on Si(001), as an example for the lanthanide oxides, well-defined experimental studies by reflection high-energy diffraction and x-ray photoelectron spectroscopy were performed under ultraclean ultrahigh vacuum conditions of molecular beam epitaxy. Complementary investigations were performed by transmission electron microscopy. We found that Nd2O3 is a candidate for replacing silicon dioxide as gate dielectric in future Si devices with suitable band gap and offset with respect to silicon. However, under ultrahigh vacuum conditions, silicide formation occurs in the initial stage of growth, which can result in large silicide inclusions and hole formation during further growth. This effect can be completely prevented by modifying the oxygen partial pressure during the interface formation and layer growth.

No abstract

We investigated the influence of additional oxygen supply and temperature during the growth of thin Gd2O3 layers on Si(001) with molecular beam epitaxy. Additional oxygen supply during growth improves the dielectric properties significantly; however, too high oxygen partial pressures lead to an increase in the lower permittivity interfacial layer thickness. The growth temperature mainly influences the dielectric gate stack properties due to changes of the Gd2O3∕Si interface structure. Optimized conditions (600°C and pO2=5×10−7mbar) were found to achieve equivalent oxide thickness values below 1nm accompanied by leakage current densities below 1mA∕cm2 at 1V.