Quantitative analysis of the interplay between InAs quantum dots and wetting layer during the GaAs capping process

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Quantum dots (QDs) are crucial in optoelectronic devices.
• Understanding the wetting layer (WL) and QD composition is vital for performance.
• InAs/GaAs heterostructures are widely studied for their unique properties.

Purpose of the Study:

• To develop a quantitative method for analyzing the InAs distribution between WL and QDs.
• To investigate the impact of capping layer (CL) growth rates on QD decomposition and composition.
• To determine the average Indium (In) content within QDs.

Main Methods:

• Quantitative analysis of InAs in WL and QDs using statistical methods.
• Calibration using strain and compositional mappings (ChemiSTEM) on WL structures.
• High-resolution transmission electron microscopy (HR-TEM) and high-resolution X-ray diffraction (HR-XRD).

Main Results:

• The area under average profiles from strain and compositional mappings effectively quantifies InAs in the WL.
• Slower GaAs CL growth rates lead to In enrichment in the WL and reduced QD height.
• Ga/In intermixing during QD decomposition significantly reduces QD height and In content.

Conclusions:

• The developed procedure accurately quantifies InAs distribution in InAs/GaAs systems.
• Capping layer growth rate is a critical parameter controlling QD properties and In content.
• Understanding these compositional changes is key to tuning the optical properties of QDs.