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$_2$. 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

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

X-ray-photoelectron-diffraction study of InAs/InP(001) heterostructures

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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)

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