Tuning the Excitonic Emission of GaAs Quantum Dots
Sprache des Vortragstitels:
Englisch
Original Tagungtitel:
Semicon Nano 2015
Sprache des Tagungstitel:
Englisch
Original Kurzfassung:
Quantum dots (QDs) have been studied intensively, as they are promising sources
of single and entangled photons on demand. In this talk, I will show how the excitonic
emission of GaAs QDs can be tuned in a wide range by combing flexible growth
protocols and post-growth strain engineering.
Highly symmetric GaAs QDs in Al0.4Ga0.6As matrix are obtained by an optimized
local-droplet-etching technique. Compared with conventional InAs/GaAs QDs, the
GaAs/AlGaAs QDs feature no complicated built-in strain and also their composition
profile is better defined, making them an ideal platform for fundamental studies as well
as for application in the red and near-infrared spectral range. Firstly, I will show the
optimized growth of low density (<1?m-2) GaAs QDs on GaAs(001) substrates, which
results in excitonic-emission linewidths down to 4 ?eV and average fine structure
splittings (FSSs) of less than 2 ?eV under non-resonant excitation [1]. Then I will present
a systematic study of FSS as a function of QD size and shape [1, 2]. Finally, I will show
how the excitonic nature of our QDs can be swapped from the conventional heavy-hole
(HH) like to light-hole (LH) like. Taking advantage of the negligible pre-strain, the
ground state of the valence band in GaAs QDs can be switched using moderate tensile
strains (~0.4%) provided by two InAlGaAs stressor layers. Different from HH excitons,
the LH excitonic emissions show three orthogonally-polarized bright optical transitions
with one polarized along the growth direction [3, 4].
Sprache der Kurzfassung:
Englisch
Vortragstyp:
Hauptvortrag / Eingeladener Vortrag auf einer Tagung
Forschungs-