Single site-controlled In(Ga)As/GaAs quantum dots: growth, properties and device integration

Area of Science:

• Quantum dot technology
• Semiconductor nanostructures
• Optoelectronics

Background:

• Site-controlled quantum dots (SCQDs) are crucial for scalable quantum technologies.
• Improving the optical quality and deterministic integration of SCQDs remains a challenge.
• Previous methods struggled to achieve narrow emission linewidths in SCQDs.

Purpose of the Study:

• To advance the growth and integration of site-controlled quantum dots.
• To enhance the optical properties of individual SCQDs.
• To demonstrate the application of SCQDs in photonic devices and nanoelectronic memories.

Main Methods:

• Advanced growth of SCQDs on pre-patterned nanoholes.
• Vertical stacking of spectrally detuned quantum dot layers.
• Utilizing vertical strain-induced coupling for accurate SCQD nucleation.
• Integration of SCQDs into photonic resonators and high electron mobility heterostructures.

Main Results:

• Reduced average emission linewidth from 2.3 meV to 600 microeV in stacked SCQD layers.
• Achieved record narrow linewidths of individual SCQDs down to approximately 110 microeV.
• Observed enhanced spontaneous emission in coupled photonic SCQD-resonator devices.
• Demonstrated deterministic integration and room-temperature flash memory operation of SCQDs.

Conclusions:

• Advanced SCQD growth techniques significantly improve optical quality and enable precise control.
• Vertically stacked and spectrally detuned QD layers are effective for single SCQD studies.
• SCQDs show great promise for next-generation optoelectronic devices and quantum information processing.
• Deterministic integration of SCQDs into functional devices like flash memory is feasible.