K. Pfennighaus

Growth of 6H–SiC on 6H–SiC(0001) by migration enhanced epitaxy controlled to an atomic level using surface superstructures

Epitaxial growth of 6H–SiC on 6H–SiC(0001) via two‐dimensional nucleation was realized at 930 °C by solid‐source molecular beam epitaxy using the alternate supply of Si and C. The deposition was controlled to an atomic level by surface superstructures. The growth was started on the (√3×√3)R30° surface which turns into the (1×1) phase upon deposition of about 1 monolayer silicon and recurs after subsequent deposition of about 1 monolayer carbon. Deviations from the monolayer deposition and, moreover, growth around substrate related defects result in the deposition of 3C–SiC.

Investigations of Stranski-Krastanov growth kinetics of Si-dots on 6H-SiC(0001)

The growth kinetics of Si dots grown on 6H-SiC(0001) by molecular beam epitaxy were studied in real time by reflection high-energy electron diffraction. The critical thickness for the Stranski–Krastanov growth mode transition was found to be kinetically delayed leading to a gradual decrease of this thickness with increasing temperature (T). At T<625 °C and coverages below the critical thickness, a post-deposition evolution of dots is clearly established. The dot growth process is, under these conditions, mainly determined by the mass transfer out of the two-dimensional layer towards the Si dots. The dots grown on top of a 1 monolayer (ML) thick wetting layer are quantum sized with typical dimensions of 5–6 nm in height and 20–30 nm in diameter after a long post-deposition evolution times at 2–3 ML coverages. Above 625 °C and coverages above the critical thickness, the dot growth is only determined by surface-diffusion kinetics resulting in the growth of larger dots.

MBE growth of quantum-size Si-dots on SiC(0001) monitored by RHEED

Abstract 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.

Hexagonal and cubic SiC thin films on SiC deposited by solid source MBE

Abstract Epitaxial growth of SiC on SiC was realized between 900 and 1100 °C by means of solid-source molecular beam epitaxy. In general, our results show that the growth mode is strongly influenced on the surface stoichiometry. In case of Si-stabilized surfaces, showing 3-fold superstructures, films grow layer-by-layer via two-dimensional nucleation even at relatively low temperatures ( 925°C and R

RHEED investigations of MBE-growth kinetics of Si on Si(111) and SiC on SiC(100)

Reflection high-energy electron diffraction has been used to study the molecular beam epitaxy-growth kinetics of Si on Si(111) and of SiC on SiC(100). By means of a simple kinematic scattering theory we have estimated diffusion barrier energy values for adatom migration and nucleation energies. Results clearly show that growth kinetics are different at low and high temperatures for both systems. At lower temperatures the nucleation can be explained by a single adatom diffusion process, whereas at higher temperatures much higher activation energies may be attributed to an island coarsening process.

Influence of growth conditions on the growth mode and layer structure in MBE-growth of SiC on SiC(0001)

Abstract Epitaxial growth of SiC on 6H-SiC(0001) was realized between 900 and 1100 °C by means of solid-source molecular beam epitaxy (MBE). In general, results show that the growth mode is strongly influenced by the surface stoichiometry. In case of Si-stabilized surface, showing 3-fold superstructures, films grow layer-by-layer via two-dimensional nucleation even at relative low temperatures (

Epitaxial growth of SiC-heterostructures on α-SiC(0001) by solid-source MBE

Epitaxial growth of SiC on α-SiC(0001) has been performed by means of solid-source molecular beam epitaxy (MBE). Low temperature (T 1200°C, with a step decrease of supersaturation, a step-flow growth mode and for the first time nucleation of both 4H- and 6H-SiC under C-rich conditions was obtained. Based on these results we have demonstrated the growth of a double-heterostructure by firstly growing a 3C-SiC film on 4H-SiC(0001) at low temperature and a subsequent growth of 4H-SiC at low supersaturation on a C-stabilized surface on top of this film. Moreover, we also propose a new model to explain quantitatively the occurrence of different growth features and polytypes under certain growth conditions.

Investigation of growth conditions for epitaxial growth of SiC on Si in the solid-source molecular beam epitaxy

Abstract Thin crystalline SiC films were grown on Si(111) using solid state evaporation at substrate temperatures between 780 and 900 °C. The growth rates were in the range between 30 and 120 nm h−1. The films were characterized by in situ reflection high-energy electron diffraction (RHEED) and ex situ transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared (IR) spectroscopy and X-ray diffraction (XRD). The films grown at high temperatures and low growth rates were found to be epitaxial. They mostly consist of twinned-cubic structure, but with increasing layer thickness hexagonal stacking sequences often were found. In the orientation distribution function full width at half maximum (FWHM) values of down to 1° were measured.