Step-flow Growth Mode Research Articles

Atomic Hydrogen-Assisted GaAs Molecular Beam Epitaxy

A continual irradiation of atomic H during the growth of GaAs in molecular beam epitaxy (MBE) has been shown to be a viable method to obtain sharp heterointerfaces and high-quality epitaxial layers. We provide some fundamentally important observations related to atomic scale mechanisms and interactions, and the growth models for atomic H-assisted homoepitaxial GaAs MBE are proposed. Atomic H has been shown to be an efficient surfactant reducing the surface and total energy of GaAs(100) that acts to promote layer-by-layer and step-flow growth mode. However, the actual growth kinetics is different depending on the growth temperature, which affects the energetic stability of atomic H adsorption on GaAs(100). Furthermore, the continual removal of surface contaminants and also the excess arsenic during the growth are thought to be another important attribute played by atomic H.

Mechanism of Multiatomic Step Formation during Metalorganic Chemical Vapor deposition Growth of GaAs on (001) Vicinal Surface Studied by Atomic Force Microscopy

The detailed behavior and mechanism of multiatomic step formation processes during metalorganic chemical vapor deposition (MOCVD) of GaAs on vicinal surfaces are systematically investigated using an atomic force microscope (AFM). Under the low growth rate condition, the step flow growth mode with regular stripe is obtained, and the final terrace width is almost independent of the substrate misorientation angle. The result suggests that the barrier height difference for surface migrating Ga atoms between the terrace site and the step site is small, and the final terrace width is mainly determined by a migration length. Three-dimensional nucleation and growth mode with irregular steps are also obtained under the high growth rate condition. However, as the AsH3 partial pressure increases, irregular steps are no longer observed. For these results, we discuss the multiatomic step formation mechanism.

{311} facets of selectively grown epitaxial Si layers on SiO2-patterned Si(100) surfaces.

A Si epitaxial layer was selectively grown on ${\mathrm{SiO}}_{2}$-patterned Si(100) with no miscut and on 1\ifmmode^\circ\else\textdegree\fi{}, 3\ifmmode^\circ\else\textdegree\fi{}, and 4\ifmmode^\circ\else\textdegree\fi{} miscut vicinal surfaces by ultrahigh-vacuum chemical-vapor deposition using disilane. On the patterned Si(100) surfaces with and without miscuts, faceted (100) layers grew. Although {111} is energetically the most stable surface, the resulting facets had {311} orientation. This means that the {311} faceting is related to the growth kinetics rather than the energetics. Macroscopically, the {311} faceting is caused by the slower growth rate of the (311) surface than that of the (100) surface. On the vicinal surfaces, the top surface of the selectively grown layer was not vicinal but had exactly (100) orientation. This indicates the ready incorporation of adatoms into the step edges of (100) terraces and the subsequent step-flow growth mode. When the flowing step reaches the end of the top surface, it is swallowed into the facet and disappears. This decreases the step density and makes the vicinal surface flat. With respect to the swallowing of the growing steps at the facet corner, we propose a microscopic model for the {311} faceting.

Interplay between evolving surface morphology, atomic-scale growth modes, and ordering duringSixGe1−xepitaxy

Atomic-scale compositional ordering in Si x Ge 1-x alloys is directly linked to the formation of coherent islands during Stranski-Krastanow growth. The vicinal surfaces associated with nonequilibrium island shapes induce a bilayer step flow growth mode, and the ordering resulting from Ge segregation at D B kinks

Transient growth in molecular beam epitaxy of Si on Si(100) vicinal surfaces

During Si molecular beam epitaxy on a Si(100) vicinal surface with monatomic height steps, we have found a transient mode which shows a characteristic behaviour in the coverage of 2 × 1 terraces. The mode consists of two competitive growth modes: a step flow growth mode and a two-dimensional nucleation growth mode. The two modes appear alternatively depending on the 2 × 1 terrace area which varies during the growth.

Transient growth in molecular beam epitaxy of Si on Si(100) vicinal surfaces

Abstract During Si molecular beam epitaxy on a Si(100) vicinal surface with monatomic height steps, we have found a transient mode which shows a characteristic behaviour in the coverage of 2 × 1 terraces. The mode consists of two competitive growth modes: a step flow growth mode and a two-dimensional nucleation growth mode. The two modes appear alternatively depending on the 2 × 1 terrace area which varies during the growth.