Investigation of various optical transitions in GaAs/Al_0.3Ga_0.7As double quantum ring grown by droplet epitaxy

Abstract

This work examines the optical transitions of a GaAs double quantum ring (DQR) embedded in Al0.3Ga0.7As matrix by photoreflectance spectroscopy (PR). The GaAs DQR was grown by droplet epitaxy (DE). The optical properties of the DQR were investigated by excitation‐intensity and temperature‐dependent PR. The various optical transitions were observed in PR spectra, whereas the photoluminescence (PL) spectrum shows only the DQR and GaAs band emissions. The various optical transitions were identified for the GaAs near‐band‐edge transition, surface confined state (SCS), DQR confined state, wetting layer (WL), spin–orbital split (EGaAs + Δo), and AlGaAs band transition. PR spectroscopy can identify various optical transitions that are invisible in PL. The PR results show that the GaAs/AlGaAs DQR has complex electronic structures due to the various interfaces resulting from DE.

Post-Annealing Effects on Optical Properties of GaAs/AlGaAs Quantum Dots Grown by Droplet Epitaxy

“…However, annealing the samples at high temperatures led to interdiffusion between the GaAs buffer and AlGaAs barrier layer and between the GaAs QD and AlGaAs. If the interdiffusion occurs, the Al composition will be changed, and this can affect the QD signal [5,8]. In order to determine the optimal an-1.…”

Optically Induced Long‐Range Coupling Studies in a Single GaAs Laterally Coupled Quantum Dot

“…Figure shows atomic force microscope (AFM) images of uncapped GaAs laterally coupled QDs on Al 0.3 Ga 0.7 As surfaces. To grow the laterally coupled QDs, droplet epitaxy (DE) was performed using a molecular‐beam‐epitaxy system equipped with a valved arsenic (As 4 ) cell . The cell was used to maintain an ultralow As background pressure and to achieve precise control of the As 4 beam equivalent pressure (BEP) during group‐III (Ga) droplet formation and crystallization of quantum nanostructures (QNs).…”

Double Quantum Ring under an Intense Nonresonant Laser Field: Zeeman and Spin-Orbit Interaction Effects

“…Transport in Coulomb-coupled double rings under a magnetic field was measured in Ref. [21], whereas Kim reported on the optical transitions in GaAs-Al 0.3 Ga 0.7 As DQRs grown by droplet epitaxy [22].…”