Browsing by Author "Ou, Ya-Wen"

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Electrically sign-reversible transverse g-factors of holes in droplet epitaxial GaAs/AlGaAs quantum dots under uniaxial stress
(2017-08-23)
Wu, Yu-Nien
;
Wu, Ming-Fan
;
Ou, Ya-Wen
;
Chou, Ying-Lin
;
Cheng, Shun-Jen
We present a theoretical investigation of anisotropic g-factor tensors of single holes confined in droplet epitaxial GaAs/AlGaAs quantum dots under electrical and mechanical controls using the gauge-invariant discretization method within the framework of four-band Luttinger-Kohn (k) over right arrow.(p) over right arrow theory. We reveal an intrinsic obstacle to realize the electrical sign reversal of the hole g-factors, being a key condition required for a full spin control in the scheme of g-tensor modulation, for the quantum dots solely with electrical bias control. Constructively, our studies show that, besides electrical gating, slightly stressing an inherently unstrained droplet epitaxial GaAs/AlGaAs quantum dot can offset the transverse hole g-factor to be nearly zero and make the electrical sign reversal of the hole g-factors feasible.
Wavelength extension beyond 1.5 mu m in symmetric InAs quantum dots grown on InP(111)A using droplet epitaxy
(2016-10)
Ha, Neul
;
Mano, Takaaki
;
Wu, Yu-Nien
;
Ou, Ya-Wen
;
Cheng, Shun-Jen
By using a C-3v symmetric (111) surface as a growth substrate, we can achieve high structural symmetry in self-assembled quantum dots, which are suitable for use as quantum-entangled-photon emitters. Here, we report on the wavelength controllability of InAs dots on InP(111)A, which we realized by tuning the ternary alloy composition of In(Al, Ga) As barriers that were lattice-matched to InP. We changed the peak emission wavelength systematically from 1.3 to 1.7 mu m by barrier band gap tuning. The observed spectral shift agreed with the result of numerical simulations that assumed a measured shape distribution independent of the barrier choice. (C) 2016 The Japan Society of Applied Physics