Self-Assembly of Symmetric GaAs Quantum Dots on (111)A Substrates: Suppression of Fine-Structure Splitting

Abstract

Great suppression of fine-structure splitting (FSS) is demonstrated in self-assembled GaAs quantum dots (QDs) grown on AlGaAs(111)A surface. Due to the three-fold rotational symmetry of the growth plane, highly symmetric excitons with significantly reduced FSS are achieved. Scanning tunneling microscopy and cross-sectional transmission microscopy demonstrate a laterally symmetric dot shape with abrupt interface. Polarized photoluminescence spectra confirm excitonic transition with FSS smaller than ∼20 µeV, a substantial reduction from that of QDs grown on (100).

Magnetic field induced valence band mixing in [111] grown semiconductor quantum dots

“…15 This growth axis has the advantage of providing in principle quantum-dot shape of the higher C 3v point symmetry. Really, small fine structure splittings in as grown [111] quantum dot structures have been recently predicted 16,17 and observed [18][19][20][21] making such structures a very promising system for entangled photon pair emission.…”

Strain-driven growth of GaAs(111) quantum dots with low fine structure splitting

“…Instead of assembling QDs, the compressive strain relaxes plastically to form dense misfit dislocation arrays. 8,9 The failure of S-K growth on (111) surfaces has driven the development of alternative (111) QD growth techniques including droplet epitaxy [10][11][12] and growth on patterned substrates. 13,14 In droplet epitaxy, metal droplets deposited onto the substrate are crystallized under arsenic vapor to form III-V semiconductor QDs.…”

“…16 Nonetheless, progress in droplet epitaxy has led to (111) QDs with narrow linewidths and low FSS. 10,11 Growth within pyramidal etch-pits on (111) substrates offers an alternative, whereby preferential growth at the bottom of each pit produces 3D QDs. However, the pitgeometry hinders light extraction from the QDs, 13 and large etch-pits are difficult to integrate into photonic resonators for high photon emission rates.…”

Intertwining of Zeeman and Coulomb interactions on excitons in highly symmetric semiconductor quantum dots

“…5 Most experimental studies of excitons confined in QDs were performed on self-assembled quantum dots (SAQDs) grown on {100} surfaces and were concerned with polarization anisotropy, [16][17][18] in-plane anisotropy of carrier effective g factors, 19,20 fine-structure splitting of neutral and charged exciton complexes, [21][22][23][24] which were induced by the shape asymmetry, and the existence of anisotropic strain and piezoelectric fields in these dots. Only recently, highly symmetric pyramidal QDs grown on {111} surfaces have emerged as interesting quantum structures in which zero fine-structure splitting of the neutral exciton was predicted 25,26 and eventually observed, [27][28][29][30] and for which the entanglement of polarized photon pairs was demonstrated. 31 It is our purpose in this paper to develop a general theoretical model of the Zeeman effects on the quantum states of excitons in highly symmetric QDs and to compare its predictions to experimental studies performed on magnetoexcitons confined in pyramidal QDs grown on (111)B GaAs substrates.…”