Valence band spectroscopy in V-grooved quantum wires

We present a combined theoretical and experimental study of the anisotropy in the optical absorption of V-shaped quantum wires. By means of realistic band structure calculations for these structures, we show that detailed information on the heavy- and light-hole states can be singled out from the anisotropy spectra {\em independently of the electron confinement}, thus allowing accurate valence band spectroscopy.Comment: To be published in Appl. Phys. Lett. (8 pages in REVTeX, two postscipt figures

Luttinger liquid behavior in weakly disordered quantum wires

We have measured the temperature dependence of the conductance in long V-groove quantum wires (QWRs) fabricated in GaAs/AlGaAs heterostructures. Our data is consistent with recent theories developed within the framework of the Luttinger liquid model, in the limit of weakly disordered wires. We show that for the relatively small amount of disorder in our QWRs, the value of the interaction parameter g is g=0.66, which is the expected value for GaAs. However, samples with a higher level of disorder show conductance with stronger temperature dependence, which does not allow their treatment in the framework of perturbation theory. Trying to fit such data with perturbation-theory models leads inevitably to wrong (lower) values of g.Comment: 4 pages, 4 figure

Electron-hole correlation effects in the emission of light from quantum wires

We present a self-consistent treatment of the electron-hole correlations in optically excited quantum wires within the ladder approximation, and using a contact potential interaction. The limitations of the ladder approximation to the excitonic low-density region are largely overcome by the introduction of higher order correlations through self consistency. We show relevance of these correlations in the low-temperature emission, even for high density relevant in lasing, when large gain replaces excitonic absorption.Comment: 4 paes 3 figure

Shape-independent scaling of excitonic confinement in realistic quantum wires

The scaling of exciton binding energy in semiconductor quantum wires is investigated theoretically through a non-variational, fully three-dimensional approach for a wide set of realistic state-of-the-art structures. We find that in the strong confinement limit the same potential-to-kinetic energy ratio holds for quite different wire cross-sections and compositions. As a consequence, a universal (shape- and composition-independent) parameter can be identified that governs the scaling of the binding energy with size. Previous indications that the shape of the wire cross-section may have important effects on exciton binding are discussed in the light of the present results.Comment: To appear in Phys. Rev. Lett. (12 pages + 2 figures in postscript

Quasiparticle properties of a coupled quantum wire electron-phonon system

We study leading-order many-body effects of longitudinal optical (LO) phonons on electronic properties of one-dimensional quantum wire systems. We calculate the quasiparticle properties of a weakly polar one dimensional electron gas in the presence of both electron-phonon and electron-electron interactions. The leading-order dynamical screening approximation (GW approximation) is used to obtain the electron self-energy, the quasiparticle spectral function, and the quasiparticle damping rate in our calculation by treating electrons and phonons on an equal footing. Our theory includes effects (within the random phase approximation) of Fermi statistics, Landau damping, plasmon-phonon mode coupling, phonon renormalization, dynamical screening, and impurity scattering. In general, electron-electron and electron-phonon many-body renormalization effects are found to be nonmultiplicative and nonadditive in our theoretical results for quasiparticle properties.Comment: 21 pages, Revtex, 12 figures enclose