  This paper presents the experimental results on research of growth processes
of GaAs layers on silicon substrates by molecular beam epitaxy. The formation
of buffer Si layer in a single growth process has been found to significantly
improve the crystalline quality of the GaAs layers formed on its surface, as
well as to prevent the formation of anti-phase domains both on offcutted
towards the [110] direction and on singular Si(100) substrates. It has been
demonstrated that the use of cyclic thermal annealing at temperatures
350-660{\deg}C in the flow of arsenic atoms makes it possible to reduce the
number of threading dislocations and increase the smoothness of the GaAs layers
surface. At the same time, the article considers possible mechanisms that lead
to an improvement in the quality of the surface layers of GaAs. It is shown
that the thus obtained GaAs layers of submicron thickness on the singular
Si(100) substrates have a mean square value of surface roughness 1.9 nm. The
principal possibility of using thin GaAs layers on silicon as templates for
forming on them light-emitting semiconductor heterostructures with active area
based on self-organizing InAs quantum dots and InGaAs quantum well is
presented. They are shown to exhibit photoluminescence at 1.2 um at room
temperature.
