E. Martinet

Structure and Formation Mechanisms of AlGaAs V-Groove Vertical Quantum Wells Grown by Low-Pressure Organometallic Chemical Vapor Deposition

The structure of AlGaAs vertical quantum well (VQW) structures grown by low‐pressure organometallic chemical vapor deposition on V‐grooved GaAs substrates was analyzed as a function of growth temperature and Al mole fraction using transmission electron microscopy and atomic force microscopy (AFM). The low‐pressure growth yields several, extremely narrow (a few nm wide) branches of Ga‐enriched VQWs at the bottom of the grooves. The variation in Al content across the VQW was evaluated by measuring the AlGaAs oxide thickness on a cleaved edge of the structure using AFM in air. The transmission electron microscopy analysis demonstrates that the different VQW branches originate from distinct nanofacets that self‐order at the bottom of the V‐groove, probably due to facet‐induced segregation of group III species.

Self Ordering and Confinement in Strained InGaAs/AlGaAs V-Groove Quantum Wires Grown by Low-Pressure Organometallic Chemical Vapor Deposition

The structure and low temperature luminescence properties of compressively strained InGaAs/AlGaAs quantum wire (QWR) arrays grown by low-pressure organometallic chemical vapor deposition on V-grooved substrates are reported. The strain gives rise to quasi-periodic undulations of the wire facets along the wire axis, resulting in ordered chains of quantum dotlike structures. Low-temperature photoluminescence shows efficient emission from the wires with narrow (as low as 9.8 meV) linewidths and relatively high intensities. At high excitation densities, several quasi-one-dimensional QWR subbands appear as a result of bandfilling, presenting virtually no energy shifts (<2 meV), even when several (⩾3) subbands are filled.

Influence of strain and quantum confinement on the optical properties of InGaAs/GaAs V-groove quantum wires

We report on the impact of quantum confinement and strain effects on the optical properties of state-of-the-art, densely stacked, In0.15Ga0.85As/GaAs V-groove quantum wires. High uniformity and efficient carrier capture lead to narrow (6 meV) and intense emission from the wires. Large optical polarization anisotropy is obtained thanks to the combined effects of lateral quantum confinement and triaxial strain. Band filling in the fundamental subband occurs at a modest carrier density (∼9×105 cm−1), and is accompanied by a small spectral blueshift of the emission. Several sharp excitonic resonances associated with two dimensionally confined subbands of dominant heavy-hole character are observed in photoluminescence excitation spectroscopy, together with a remarkably small Stokes shift (3 meV). The subband separations (∼24 meV) are nearly independent of the wire thickness, as the nonuniform Indium composition across the structure is found to dominate the lateral confinement for thick wires. Such strained qua...

Selective carrier injection into V-groove quantum wires

We have observed selective carrier injection into GaAs/AlGaAs V-groove quantum wires (QWRs) via self-ordered vertical quantum wells (VQWs). Room-temperature I–V characteristics of QWR diodes show a turn-on voltage lower by 0.2 V as compared with planar QW diodes, consistent with the band-gap reduction of 0.2 eV at the vertical QW. This selective injection results in narrow linewidth electroluminescence (∼5 nm at 300 K) emanating exclusively from the QWR from 10 K up to 300 K.

Effect of indium segregation on optical properties of V-groove InGaAs/GaAs strained quantum wires

Self-ordered, strained InGaAs/GaAs quantum structures are grown on V-grooved GaAs substrates. The lateral patterning of these nonplanar heterostructures allows the growth of defect-free strained structures with thickness exceeding that achieved with planar epitaxy. Indium segregation at the bottom of the groove results in the formation of a vertical InGaAs quantum-well structure with In-enriched composition. We studied in detail the influence of nominal thickness and In content on the photoluminescence peak energy of these quantum wires. Room-temperature emission at 1.16 μm with a relatively narrow linewidth (30–35 meV) is achieved as a demonstration of the potential of this approach for fabricating long-wavelength semiconductor light sources on GaAs substrates.

Efficient, narrow linewidth excitonic emission at room temperature from GaAs/AlGaAs V-groove quantum wire light-emitting diodes

We report on efficient, narrow linewidth exciton recombination in GaAs/AlGaAs V-groove quantum wire light-emitting diodes at room temperature. The high efficiency is due to a selective carrier injection mechanism resulting in an estimated internal quantum efficiency of ∼20% with an electroluminescence (EL) linewidth as narrow as 15 meV. The thermal broadening contribution to the linewidth is 6 meV due to exciton scattering with optical phonons. An analysis of the EL peak shift in a magnetic field points out the typical superlinear behavior of the excitonic binding energy for a quantum wire.

Two-dimensional quantum-confined Stark effect in V-groove quantum wires: Excited state spectroscopy and theory

We report on the electric field effects in photoluminescence (PL) and PL excitation (PLE) measurements of reverse-biased GaAs V-groove quantum wires. We observe large redshifts (9 meV at −65 kV/cm) of PL and PLE peaks as well as field dependent intensity and polarization anisotropy variations, which are analyzed by a two-dimensional quantum confined Stark effect model.

Low-pressure OMCVD growth of AlGaAs vertical quantum wells on non-planar substrates

Abstract AlGaAs vertical quantum well structure were formed by low-pressure (20 mbar) organometallic chemical vapor deposition on V-grooved substrates. Ga segregation in the wells of these structures was evidenced by means of atomic force microscopy and photoluminescence experiments. Transmission electron microscopy cross sections resolve different branches in the well. This substructure, whose definition is enhanced in low-pressure growth, is associated with the formation of specific facets at the bottom of the grooves. The dependence of the growth rate on the crystallographic facet and the Al mole fraction is the key mechanism for the establishment of the self-limiting profile in the V-grooves.

Strained V-groove quantum wires in multidimensional microcavities

Reference LPN-ARTICLE-2000-004doi:10.1016/S0921-5107(99)00553-XView record in Web of Science Record created on 2008-02-29, modified on 2017-05-12

Direct observation of new transitions in the absorption spectra of a V-groove quantum wire waveguide

We report on the direct absorption measurement of the polarization selection rules in a V-groove QWR waveguide. Attenuation measurements in a 1 mm long waveguide were performed from 10 K up to room temperature. These measurements yielded the QWR DOS selection rules for lateral (TE) and vertical (TM) confinement directions. 1D heavy-hole like e(n)h(n) subband features were observed in the TE absorption spectra. Effective mass and 4 x 4 k . p models have been used to evaluate the band to band absorption. For TM polarization, no absorption is observed at the e(1)h(1) transition, but a dominant feature appears corresponding to a quasi light-hole transition (e(1)h(7)). An absorption feature is also detected at the e(1)h(2) transition. This is a new genuine QWR transition with no analog in quantum wells: the theoretical analysis shows that it arises both from valence hand mixing at k = 0 and from symmetry breaking at the heterostructure level, despite the mirror symmetry of the structure.