Effect of gallium termination on InGaAs wetting layer properties in droplet epitaxy InGaAs quantum dots

TL;DR

This study examines how gallium termination influences the formation and optical properties of InGaAs wetting layers in droplet epitaxy quantum dots, revealing that increased Ga reduces wetting layer emission.

Contribution

It demonstrates that Ga termination prior to quantum dot growth significantly suppresses wetting layer emission, offering a new approach to control quantum dot properties.

Findings

InGaAs wetting layer presence confirmed via spectroscopy and microscopy.

Ga deposition reduces wetting layer emission wavelength.

Wetting layer becomes indistinguishable from GaAs emission with increased Ga.

Abstract

Self-assembled quantum dots based on III-V semiconductors have excellent properties for applications in quantum optics. However, the presence of a 2D wetting layer which forms during the Stranski-Krastanov growth of quantum dots can limit their performance. Here, we investigate wetting layer formation during quantum dot growth by the alternative droplet epitaxy technique. We use a combination of photoluminescence excitation spectroscopy, lifetime measurements, and transmission electron microscopy to identify the presence of an InGaAs wetting layer in these droplet epitaxy quantum dots, even in the absence of distinguishable wetting layer photoluminescence. We observe that increasing the amount of Ga deposited on a GaAs (100) surface prior to the growth of InGaAs quantum dots leads to a significant reduction in the emission wavelength of the wetting layer to the point where it can no longer be distinguished from the GaAs acceptor peak emission in photoluminescence measurements.