GaAs surface passivation for InAs/GaAs quantum dot based nanophotonic devices

Area of Science:

• Materials Science
• Quantum Engineering
• Nanotechnology

Background:

• Close-to-surface InAs/GaAs quantum dots (QDs) suffer from oxidation and surface defects, degrading their optical properties.
• Effective passivation is crucial for preserving QD performance in optoelectronic devices.

Purpose of the Study:

• To evaluate and compare different passivation techniques for near-surface InAs/GaAs QDs.
• To identify passivation methods that enhance optical properties and ensure long-term stability.

Main Methods:

• Investigated N-passivation using hydrazine, hydrazine + AlOₓ (atomic layer deposition), and plasma-enhanced ALD of AlNₓ.
• Benchmarked passivation effectiveness by measuring emission linewidths and photocarrier decay rates.
• Assessed long-term stability and impact on surface recombination velocity.

Main Results:

• All three methods reduced GaAs surface oxidation and enhanced room-temperature photoluminescence (PL) intensity.
• Hydrazine + AlOₓ and AlNₓ showed long-term passivation stability, with AlNₓ being significantly more effective.
• AlNₓ passivation reduced spectral diffusion and surface recombination velocity by three orders of magnitude, increasing PL signal ~1030 times.

Conclusions:

• AlNₓ passivation offers exceptional long-term stability and significantly improves optical properties of InAs/GaAs QDs.
• This technique is highly promising for practical applications like quantum light sources utilizing QDs near air interfaces.