  Cross-sectional scanning tunneling microscopy (X-STM) was employed to
characterize the InAs submonolayer quantum dots (SMLQDs) grown on top of a
Si-doped GaAs(001) substrate in the presence of (2X4) and c(4X4) surface
reconstructions. Multiple layers were grown under different conditions to study
their effects on the formation, morphology and local composition of the SMLQDs.
The morphological and compositional variations in SMLQDs were observed by both
filled and emptystate imaging. A detailed analysis of indium segregation in the
SMLQDs layers was described by fitting local indium concentration profile with
a standard segregation model. A strong influence of arsenic flux over the
formation of the SMLQDs and indium incorporation was observed and reported. We
investigated the well-width fluctuations of the InGaAs quantum well (QW) in
which SMLQDs were formed . The monolayer fluctuations of the well width were
negligible compared to the more pronounced compositional fluctuations in all
the layers. Keywords: Submonolayer quantum dots, Surface reconstruction, X-STM,
Indium segregation
