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We investigate molecular beam epitaxial overgrowth of Si template layers produced by different approaches on single-crystalline oxide grown on Si(111). Three approaches based on modified solid-phase epitaxy were found to be suitable for the subsequent Si epitaxial overgrowth. The crystalline quality and interface properties of single-crystalline silicon on single-crystalline oxide grown on Si(111) make the obtained structures suitable for silicon-on-insulator applications. First measurements of electrical properties of p-type samples indicate good electrical properties of the top Si layer. Supplemental investigations demonstrate that Si layers with thickness in the range of 10 nm remain stable during thermal annealing up to 900 °C in an ultra-high vacuum.

We studied the growth and electrical properties of single crystalline mixed (Nd1 − xGdx)2O3 (NGO) thin films and compared the results with those of the binary Gd2O3 and Nd2O3 thin films, respectively. Epitaxial ternary NGO thin films were grown on Si(100) substrates using modified solid state molecular beam epitaxy. The films were characterized physically using various techniques. The capacitance equivalent oxide thickness of a 4.5 nm NGO thin film extracted from capacitance–voltage (C–V) characteristics was 0.9 nm, which is lower than all values reported earlier for other crystalline oxides. The leakage current density and the density of interface traps were 0.3 mA/cm2 at |Vg − VFB| = 1 V and 1.4 × 1012/cm2, respectively. These excellent electrical properties of NGO thin films demonstrate that such ternary oxides could be one of the promising candidates for gate dielectrics in the upcoming generations of complementary metal oxide semiconductor (CMOS) devices.

The molecular beam epitaxial growth of Si on SiC(0001), exhibiting a Stranski–Krastanov mode, was investigated by reflection high-energy electron diffraction. Several surface superstructures were observed in the initial stage of growth. After exceeding a critical coverage, Si island formation sets in. Under near-equilibrium conditions, the critical coverage was 1.4 monolayers and corresponds to the occurrence of a 3×3 superstructure remaining as a wetting layer after the island formation. Island formation at high deposition rates (R) and low temperatures (T) is kinetically delayed, which can be described as function of R and the diffusivity D by a relationship t c ∝ R/D . Si islands, which were relatively uniform size of several nm with a density of 1011 cm−2, were obtained under these conditions. At lower R values the critical thickness is only a function of T, indicating that the incorporation time of adatoms is the relevant time scale for surface diffusion. Ordered arrays of small dots were also grown on vicinal surfaces at higher T and lower R values, which can be attributed to a lower diffusivity at step edges, acting as perfect sinks for the Si adatoms. Furthermore, two different kinds of islands were found with a (111)/(0001) and (110)/(0001) epitaxial relationship.

Due to the large misfit (20%), Si grows in Stranski–Krastanov mode on SiC(0001) leading to the formation of Si islands with quantum-size (quantum dot) dimensions in the range of 2–6 nm in height and 10–25 nm in diameter after the transition from two-dimensional (2D) to 3D growth mode at coverages >1.25 monolayers (ML). The growth mode transition and the post growth evolution of the system towards equilibrium surface conditions by dot formation was studied in real time at temperatures between 475 and 825°C and coverages in the range of 2 ML by recording the RHEED intensities of both the specular beam and the (222)-Si-bulk spot. From that we analysed the temperature-dependent dynamic processes leading to dot formation. Above 625°C, the formation of Si dots takes place within a sub-ML range above 1.25 ML. At these temperatures, the obtained activation energy of 0.6 eV for the dot growth indicates that surface diffusion is the dominant process. Below 625°C, the occurrence of RHEED specular beam intensity oscillations indicates a 2D growth mode also at higher coverages. However, after the deposition was finished, the specular beam intensity decreased, and simultaneously, a 3D Si diffraction pattern occurred due to the formation of Si islands. The activation energy for the island growth process at these lower temperatures was determined to be much higher (2.1 eV), indicating a more complex process due to the mass transfer out of the 2D layer towards the Si islands.

The controlled growth of SiC heteropolytypic structures consisting of hexagonal (α-) and cubic (3C-) polytypes has been performed by solid-source molecular beam epitaxy. On on-axis substrates, 4H/3C/4H-SiC(0001) and 6H/3C/6H-SiC(0001) structures were obtained by first growing some nanometers thick 3C-SiC layer at lower temperatures (1550 K) and Si-rich conditions, and subsequent growth of α-SiC on top of the 3C-SiC layer at higher temperatures (1600 K) under more C-rich conditions. On off-axis substrates, multi-heterostructures consisting of 4H/3C- or 6H/3C-stacking sequences were also obtained by first nucleating selectively wire-like 3C-SiC nuclei on the terraces of well-prepared off-axis α-SiC(0001) substrates at low T (< 1500 K). Next, SiC was grown further in a step-flow growth mode at higher T and Si-rich condition. After the growth many wire-like regions consisting of 3C-SiC were found within the hexagonal SiC layer material matrix indicating a simultaneous step-flow growth of both the cubic and the hexagonal SiC material.

The growth and structure of Si- and Ge-nanocrystals was investigated using high resolution X-ray diffraction (HRXRD) and atomic force microscopy (AFM). AFM-images were used to determine the lateral and vertical dimensions of the nanocrystal. HRXRD measurements show clearly that Si- and Ge-nanocrystals grow on 6 H –SiC(0001) preferentially in two different orientations — 〈111〉 and 〈110〉 — with respect to the surface normal. The growth of Ge-nanocrystals on Si-rich 6 H –SiC(0001) surfaces leads to the formation of Si/Ge-alloy nanocrystals. Both types of nanocrystals grow coherently with respect to the substrate. Hence, due to the respective lattice mismatch, the degree of coherence was found to be much better for Si-nanocrystals.

SiC thin films on Si(111) were grown using solid state evaporation at relatively low temperatures. Growth rates of 3–10 nm min −1 have been achieved at 750–900 °C. Results obtained from IR spectroscopy, Auger electron spectroscopy and X-ray diffraction indicate good crystalline growth at T > 800 °C, in the case of a stoichiometric composition. The crystallinity was found to be deteriorated in layers with excess Si or C. In addition, shifts in the IR absorption peak indicate that the non-stoichiometric layers were highly stressed. Annealing of non-stoichiometric layers shifts the peak to the position obtained for stoichiometric layers.