Site-controlled self-assembled InAs quantum dots grown on GaAs substrates

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Achieving atomically-flat surfaces is crucial for controlled semiconductor growth.
• Nano-hole patterning on substrates can influence subsequent material deposition.
• Buffer layers play a key role in surface morphology and material integration.

Purpose of the Study:

• To investigate the effect of GaAsSb buffer layers on GaAs substrate surface morphology.
• To explore the formation of site-controlled self-assembled InAs quantum dots (QDs) on patterned substrates.
• To understand the role of antimony (Sb) incorporation in adatom migration and surface smoothing.

Main Methods:

• Growth of thin GaAsSb buffer layers on GaAs substrates with pre-formed nano-holes.
• Local atomic-force-microscopy anode oxidation for nano-hole formation.
• Comparison of surface roughness between GaAsSb-buffered and GaAs-buffered samples.
• Deposition of InAs below critical thickness on buffer layers for QD formation.

Main Results:

• Atomically-flat surfaces were achieved with GaAsSb buffer layers on nano-hole patterned GaAs substrates.
• GaAs buffer layers showed increased root-mean-square roughness with increasing thickness.
• Sb incorporation in GaAsSb layers enhanced adatom migration, contributing to surface smoothing.
• Site-controlled self-assembled InAs QDs were successfully formed using 1.3 monolayer InAs coverage on nano-hole patterned substrates with buffer layers.

Conclusions:

• Thin GaAsSb buffer layers on nano-hole patterned GaAs substrates promote atomically-flat surfaces.
• The presence of Sb significantly enhances adatom migration, leading to improved surface morphology.
• This approach facilitates the site-controlled self-assembly of InAs quantum dots, offering potential for advanced device fabrication.