12 research outputs found
Growth of GaInTlAs layers on InP by molecular beam epitaxy
International audienceGrowth of GaInTlAs alloys on InP001 has been attempted by solid source molecular beam epitaxy. Thallium incorporation into Ga 1x In x As matrices was studied as a function of substrate temperature, arsenic overpressure, matrix composition, and growth rate. At high temperatures 350 °C thallium evaporates, whereas at intermediary temperatures 270-350 °C thallium segregates into droplets on the surface. Only in the low temperature range 180-260 °C can thallium be incorporated in some conditions, leading to mirror-like surfaces. Up to 18% Tl content was incorporated into a Ga 0.70 In 0.30 As matrix and up to 40% Tl into a GaAs matrix. For these high Tl concentrations, Tl droplets are avoided and Tl incorporation is achieved only when using high arsenic pressures. However, this limits surface adatom diffusion and leads to amorphous, polycrystalline, or twinned materials. Finally, a narrow window for single-crystal growth has been found for low Tl contents 4% using optimized growth conditions with low V/III pressure ratios and high growth rates
Inclusion of Experimental Information in First Principles Modeling of Materials
We propose a novel approach to model amorphous materials using a first
principles density functional method while simultaneously enforcing agreement
with selected experimental data. We illustrate our method with applications to
amorphous silicon and glassy GeSe. The structural, vibrational and
electronic properties of the models are found to be in agreement with
experimental results. The method is general and can be extended to other
complex materials.Comment: 11 pages, 8 PostScript figures, submitted to J. Phys.: Condens.
Matter in honor of Mike Thorpe's 60th birthda
X-ray-photoelectron-diffraction study of InAs/InP(001) heterostructures
International audienc
Etude des structures MIS sur InP réalisées avec une double couche anodique
Des composants MISFET de bonne qualité sont obtenus avec une double couche alumine-oxyde natif comme isolant de grille. Dans cet article, la loi de croissance de ces deux couches et la composition chimique de l'oxyde interfacial sont étudiées par ellipsométrie et XPS. L'oxyde natif est très proche de In (PO3)3. La comparaison des courbes capacité-tension montre que l'oxyde interfacial doit être plus épais que 5 nm pour obtenir de bonnes propriétés électriques
Etude des structures MIS sur InP réalisées avec une double couche anodique
High quality InP MISFET's with Al2O3/native oxide double layer as gate insulator have been reported. In this paper, the oxide growth law of the double layer and the chemical composition of the interfacial oxyde are studied using ellipsometry and XPS. The native oxide is found to be very similar to In(PO3)3. Capacitance-voltage measurements revealed that the thickness of this interfacial oxide must be thicker than 5 nm to obtain the best electrical properties for the interface.Des composants MISFET de bonne qualité sont obtenus avec une double couche alumine-oxyde natif comme isolant de grille. Dans cet article, la loi de croissance de ces deux couches et la composition chimique de l'oxyde interfacial sont étudiées par ellipsométrie et XPS. L'oxyde natif est très proche de In (PO3)3. La comparaison des courbes capacité-tension montre que l'oxyde interfacial doit être plus épais que 5 nm pour obtenir de bonnes propriétés électriques
In situ XPS investigation of indium surface segregation for Ga1−xInxAs and Al1−xInxAs alloys grown by MBE on InP(001)
International audienc
Two dimensional Sr silicate grown on Si(001) studied using X-ray Photoelectron Spectroscopy
We used X-ray Photoemission Spectroscopy (XPS) to study the
structural and chemical properties of SrO grown by Molecular Beam
Epitaxy (MBE) on Si(001) substrates in the following conditions: (i)
low temperature growth at 30°C and (ii) high temperature
growth at 500°C. The crystalline quality of the film deposit
was controlled in-situ by Reflection High-Energy Electron
Diffraction (RHEED). The results show the growth, at low temperature
of epitaxial SrO; and at high temperature the formation of
crystalline silicate