Showing papers by "Eric Tournié published in 1993"

Virtual‐surfactant epitaxy of strained InAs/Al0.48In0.52As quantum wells

Abstract: The solid‐source molecular beam epitaxy growth of strained InAs films embedded in an Al0.48In0.52As matrix on InP substrates is studied by in situ reflection high‐energy electron diffraction. Under standard As stable conditions, the highly (3.2%) strained InAs film grows on Al0.48In0.52As in the Stranski–Krastanov mode. Islanding starts at a thickness of 8 monolayers. On the contrary, when growing InAs under In stable conditions, islanding is inhibited. The highly reactive In stable surface imposes kinetic limitations to the sticking atoms and forces two‐dimensional nucleation, thus acting as a virtual surfactant. This growth technique produces samples of superior quality and opens a new route for the preparation of strained heterostructures.

Analysis of epitaxial GaxIn1−xAs/InP and AlyIn1−yAs/InP interface region by high resolution x‐ray diffraction

Abstract: A detailed strain analysis of high resolution x‐ray diffraction patterns taken from GaxIn1−xAs and AlyIn1−yAs layers grown lattice matched on (001) InP substrates shows the existence of distinct interface regions Our dynamical diffraction model allows us to detect buried interface layers with submonolayer resolution and differences in composition of less than 1% from the rest of the epilayer Comparison between experimental and theoretical rocking curves reveals that the interface region between epilayer and substrate comprises 2 monolayers InAs plus GaxIn1−xAs (or AlyIn1−yAs) interlayer with different group III element ratios

Long-wavelength strained-layer InAs/GaInAs single-quantum-well laser grown by molecular beam epitaxy on InP substrate

Abstract: Laser emission is reported for the first time from a 10 monolayer-wide highly strained (3.2%) InAs single quantum well confined by Ga/sub 0.47/In/sub 0.53/As layers. At 80 K the emission spectrum of broad-area laser diodes is centred at 1.836 mu m, the threshold current-density is approximately 500 A/cm/sup 2/ and the characteristic temperature is T/sub 0/ approximately=30 K. CW operation is achieved up to 110 K with narrow-stripe devices but at shorter wavelength, due to increased losses and filling of the quantum-well energy levels.

Virtual-surfactant-induced wetting in strained-layer heteroepitaxy

Abstract: We show that surface stoichiometry and growth mode are intimately related for heteroepitaxy of InAs on GaO0.47In0.53As. Under As-stable conditions during molecular beam epitaxy, the high strain of the InAs film induces a morphological phase-transition from layer-by-layer to island nucleation. In contrast, under In-stable conditions without direct As4 flux, islanding is inhibited. The In-stabilized surface imposes limitations to the migration of both As and In adatoms and forces layer-by-layer nucleation, thus acting as a virtual surfactant.

Overlayer strain: A key to directly tune the topography of high‐index semiconductor surfaces

Abstract: The surface topography of GaxIn1−xAs and InAs layers grown by solid‐source molecular‐beam epitaxy on (311)‐InP and (311)‐GaAs substrates, respectively, is investigated in situ by reflection high‐energy electron diffraction. In a wide temperature range, the (311)‐GaxIn1−xAs surfaces are corrugated on a nanometer scale in a way similar to that previously reported for (311)‐GaAs surfaces [R. Notzel, N. N. Ledentsov, L. Daweritz, M. Hohenstein, and K. Ploog, Phys. Rev. Lett. 67, 3812 (1991)]. Moreover, the period of the corrugations varies with the overlayer strain which we demonstrate to be the key parameter to control the surface topography.

Optical properties of InAs quantum wells emitting between 0.9 mu m and 2.5 mu m

Abstract: InAs/AlxGa0.48-xIn0.52As single and multiple quantum wells (QWS) grown in InP by modified solid source molecular beam epitaxy are investigated by photoluminescence (PL) spectroscopy. By adjusting the QW thickness between 2 and 16 monolayers (ML) and the barrier composition between Al0.48In0.52As and Ga0.47In0.53As, the PL emission can be tuned from 1.0 to 2.2 mu m. The excitonic nature of the low-temperature recombinations and the observations of luminescence at room temperature demonstrate the high quality of the samples and the potential of the InAs/AlxGa0.48-xIn0.52As system for optoelectronic device applications.

Surface stoichiometry and interface formation during molecular-beam epitaxy of strained InAs/AlxGa0.48-xIn0.52As heterostructures

Abstract: We show that the surface stoichiometry of the film—i.e., cation‐ or anion‐stable surface—provides a unique means to control the interface formation and sample quality during molecular‐beam epitaxy of strained InAs films buried in an AlxGa0.48−xIn0.52As matrix lattice matched to InP substrates. When the highly (3.2%) strained InAs films are grown under As‐stable conditions, islanding occurs which leads to defected interfaces. On the contrary, under In‐stable conditions islanding of the InAs films is prevented and high quality strained interfaces are obtained.

Low-density band-filling in strained InAs quantum wells

Abstract: We study the low-temperature photoluminescence (PL) of strained InAs single quantum wells (SQWs) embedded in a Ga0.47In0.53As matrix grown on InP substrates by modified solid-source molecular beam epitaxy. The spectra are interpreted in the frame of a two-level rate equation model describing the carrier dynamics in the structures. We show that band-filling occurs in these QWs for an excitation power as low as 30 Wcm−2. Moreover, the spectra reveal that the band-filling results from the rapid population of the hole subband. This observation highlights the low in-plane heavy-hole mass in the compressively strained film. Our results therefore demonstrate the high potential of InAs/Ga0.47In0.53As QW nonlinear optical devices operating in the mid-IR wavelength range.

Strained InAs/AlxGa0.48 − xIn0.52As heterostructures: a tunable quantum well materials system for light emission from the near-IR to the mid-IR

Abstract: We report on spontaneous and simulated emission from strained InAs quantum wells (QWs) embedded in an Al x Ga 0.48 − x In 0.52 As matrix grown on InP substrates by solid-source molecular-beam epitaxy. By adjusting the QW width between 2 and 23 monolayers and/or the barrier composition between Al 0.48 In 0.52 As and Ga 0.47 In 0.53 As, the low temperature photoluminescence can be tuned between 1.0 μm and 2.2 μm. Efficient room temperature luminescence is achieved up to 2.4 μm which is the longest wavelength reported for QWs grown on InP substrates. Finally, we demonstrate the first stimulated emission near 1.3 μm and 1.8 μm at 80 K in this materials system. These results thus enlarge the wavelength range of applications achievable with InP-based materials.