Large anisotropy of electron and hole<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>g</mml:mi></mml:math>factors in infrared-emitting InAs/InAlGaAs self-assembled quantum dots

Abstract

A detailed study of the $g$-factor anisotropy of electrons and holes in InAs/${\mathrm{In}}_{0.53}{\mathrm{Al}}_{0.24}{\mathrm{Ga}}_{0.23}\mathrm{As}$ self-assembled quantum dots emitting in the telecom spectral range of $1.5--1.6\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{m}$ (around 0.8 eV photon energy) is performed by time-resolved pump-probe ellipticity technique using a superconducting vector magnet. All components of the $g$-factor tensors are measured, including their spread in the quantum dot (QD) ensemble. Surprisingly, the electron $g$ factor shows a large anisotropy changing from ${g}_{\mathrm{e},x}=\ensuremath{-}1.63$ to ${g}_{\mathrm{e},z}=\ensuremath{-}2.52$ between directions perpendicular and parallel to the dot growth axis, respectively, at an energy of 0.82 eV. The hole $g$-factor anisotropy at this energy is even stronger: $|{g}_{\text{h},x}|=0.64$ and $|{g}_{\text{h},z}|=2.29$. On the other hand, the in-plane anisotropies of electron and hole $g$ factors are small. The pronounced out-of-plane anisotropy is also observed for the spread of the $g$ factors, determined from the spin dephasing time. The hole longitudinal $g$ factors are described with a theoretical model that allows us to estimate the QD parameters. We find that the QD height-to-diameter ratio increases while the indium composition decreases with increasing QD emission energy.