Optical properties of remotely doped AlAs/GaAs coupled quantum wire arrays. I. Periodic quantum confinement and localization of minority carriers

We perform low-temperature optical experiments on remotely doped lateral superlattices epitaxially grown on vicinal GaAs substrates. This quantum wire system provides a degenerate electron gas of density $n_s\simeq 8\times {10}^{11}\hspace{0.5em}{\mathrm{cm}}^{-2}$ subjected to a tunable one-dimensional periodic potential of amplitude $\simeq 20\hspace{0.5em}\mathrm{meV}$ and period $\simeq 30\hspace{0.5em}\mathrm{nm},$ i.e., at the scale of its Fermi energy ${(E}_F\simeq 25\hspace{0.5em}\mathrm{meV})$ and Fermi wavelength $\left({\lambda }_F\simeq 30\hspace{0.5em}\mathrm{nm}\right).\mathrm{}$ We show that the one-dimensional quantum confinement strongly affects both photoluminescence and photoluminescence excitation properties of the degenerate electron system. Through a careful analysis of the optical emission and absorption linear polarization spectra together with their temperature dependence, we distinguish between features due to (i) the periodic one-dimensional confinement and (ii) the localization anisotropy of photocreated valence-band carriers.