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Communication Dans Un Congrès Année : 2015

Capping and decapping GaAs nanowires with As for preventing oxidation and for epitaxial shell growth

Résumé

Semiconductor nanowire-based materials are building blocks for future electronic and photonic devices. Due to their nanometric diameter and the efficient elastic relaxation at the lateral surface, nanowires (NWs) can accommodate more strain, and thus minimize lattice-matching constraints, inevitable in conventional thin film growth. In order to improve the physical properties of such nanowires and to develop electronic devices, core shell structure has been intentionally constructed. However preparing core/shell nanowires with good quality is quite challenging for the necessity of the perfect control of the core/shell interface. As known, oxidation is one of the most common processes which change the properties of the surface, in turn, affect the performance of materials. In consideration of the small dimension and the extreme large specific surface area, semiconductor NWs core materials have a higher tendency to be oxidized in the air, especially when an epitaxial shell made of heterogeneous materials is pursued which is obligated to be grown with a different reactor. However, the passivation preventing NWs from the oxidation is less studied. In this work, self-catalyzed GaAs NWs were grown by molecular beam epitaxy (MBE) on silicon substrate. The morphology of NWs is uniform, about 50 nm in diameter and 1 μm in length, while the surface density is as high as 7 NW/μm2. To obtain a better understanding of the growth mechanism, the effect of different experimental parameters were investigated, including the effect of the substrate orientation (001), (111) and (110), the pre-deposition temperature of the catalyst, the gallium and arsenic flux and the temperature and time of the growth. Aiming to regrow an epitaxial shell around the as-prepared GaAs NWs in another reactor after an air exposure, chemical surface information on NWs was gathered by performing TEM and XPS measurements. A typical GaAs NW has quite smooth lateral facets with a thin amorphous layer outside which is composed of gallium and arsenic oxides, attributed to the oxidation in air. Such oxidation might affect the subsequent fabrication of the core-shell structure by introducing structural defects at the interface. Thus we propose a reversible arsenic-capping method without introducing any other impurities at the interface in order to exclude such difficulties. By using this method, the growth of shell materials is still under studied and will be reported later.
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Dates et versions

hal-01489620 , version 1 (14-03-2017)

Identifiants

  • HAL Id : hal-01489620 , version 1

Citer

Xin Guan, Jeanne Becdelievre, Abdennacer Benali, Claude Botella, Geneviève Grenet, et al.. Capping and decapping GaAs nanowires with As for preventing oxidation and for epitaxial shell growth. 8èmes Entretiens pour la recherche GEC-Beihang, 2015, Marseille, France. ⟨hal-01489620⟩
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