Molecular beam epitaxial growth of III-V semiconductor ... - KOBRA

patterns indicating a 2D smooth surface construction prior to the
MBE growth.
The evolution of size, density and shape of the QDs are ex-situ characterized
by atomic-force microscopy (AFM) and transmission electron
microscopy (TEM). The InAs QDs density is strongly increased
from 10 8 to 10 11 cm −2 at V/III ratios in the range of 15-35 (beam
equivalent pressure values). InAs QD formations are not observed
at temperatures of 500 ◦ C and above. Growth experiments on (111)
substrates show orientation dependent QD formation behaviour. A
signicant shape and size transition with elongated InAs quantum
dots and dashes has been observed on (111) orientation and at higher
Indium-growth rate of 0.3 ML/s. The 2D strain mapping derived
from high-resolution TEM of InAs QDs embedded in silicon matrix
conrmed semi-coherent and fully relaxed QDs embedded in defectfree
silicon matrix. The strain relaxation is released by dislocation
loops exclusively localized along the InAs/Si interfaces and partial
dislocations with stacking faults inside the InAs clusters.
The site controlled growth of GaAs/In 0.15 Ga 0.85 As/GaAs nanostructures
has been demonstrated for the rst time with 1 µm spacing and
very low nominal deposition thicknesses, directly on pre-patterned Si
without the use of SiO 2 mask.
Thin planar GaP layer was successfully grown through migration enhanced
epitaxy (MEE) to initiate a planar GaP wetting layer at the
polar/non-polar interface, which work as a virtual GaP substrate, for
the GaP-MBE subsequently growth on the GaP-MEE layer with total
thickness of 50 nm. The best root mean square (RMS) roughness
value was as good as 1.3 nm. However, these results are highly encouraging
for the realization of III-V optical devices on silicon for
potential applications.