First-step nucleation growth dependence of InAs/InGaAs/InP quantum dot formation in two-step growth.

Area of Science:

• Materials Science
• Semiconductor Physics
• Nanotechnology

Background:

• Two-step growth is crucial for high-quality mid-infrared emissive Indium Arsenide/Indium Gallium Arsenide/Indium Phosphide (InAs/InGaAs/InP) quantum dots (QDs).
• Optimizing the first-step nucleation growth significantly impacts QD size distribution, density, and crystal quality.

Purpose of the Study:

• Investigate the effect of the V/III ratio during first-step nucleation on InAs QD formation using metal-organic vapor phase epitaxy (MOVPE).
• Determine optimal conditions for achieving high-density, narrow size distribution, and high-quality InAs QDs for mid-infrared emission.

Main Methods:

• Utilized metal-organic vapor phase epitaxy (MOVPE) for InAs QD growth.
• Systematically varied the V/III input flux ratio during the first-step nucleation phase.
• Analyzed QD characteristics including size distribution, dot density, and emission wavelength.

Main Results:

• Observed contrasting behaviors in QD formation by adjusting the V/III ratio.
• Achieved high-density InAs QDs (2.5 × 10^10 cm^-2) with narrow size distribution (∼1 nm standard deviation).
• Successfully formed InAs QDs emitting at wavelengths greater than 2.15 µm by reducing the V/III ratio to zero in the first-step nucleation.

Conclusions:

• Reducing the V/III ratio to zero during first-step nucleation is critical for forming high-quality, high-density InAs QDs.
• Optimized nucleation conditions enable the growth of InAs QDs suitable for mid-infrared emission applications.
• First-step nucleation strategy directly influences the performance of two-step grown quantum dots.