Cross-sectional scanning tunneling microscopy of InAs/GaAs(001) submonolayer quantum dots

TL;DR

This study uses cross-sectional scanning tunneling microscopy to analyze the morphology, composition, and indium segregation in InAs submonolayer quantum dots grown on GaAs(001), revealing the effects of growth conditions and arsenic flux.

Contribution

It provides detailed insights into the formation, composition, and indium segregation of SMLQDs using X-STM, highlighting the influence of surface reconstruction and arsenic flux on quantum dot properties.

Findings

Indium segregation profiles fit well with a standard segregation model.

Arsenic flux significantly affects SMLQD formation and indium incorporation.

Well-width fluctuations are negligible compared to compositional fluctuations.

Abstract

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