Papers by Keyword: Islands

Abstract: Successively forming GaSb islands by solid-phase epitaxy and covering them with a silicon layer, a nanostructured material containing 4 layers of GaSb nanocrystals (NCs) was grown on Si (111) surface. Due to a small size of the NCs (average height ~ 1.7 nm, average lateral size ~ 14 nm) and, as a consequence, to a significant quantum-size effect, a high electrical conductivity (~ 100 Ω^-1·cm^-1 at 600 K) together with a low thermal conductivity (~ 1 – 1.5 W·m^-1·K^-1 at 600 K) was obtained in the nanostructured material Si/NC_GaSb/Si. As a result, the thermoelectric figure of merit of the material has reached 0.82 at 600 K.

Abstract: This article established indicators system and Gray-connection method of Islands stainable development appraisement basing on the domestic and abroad studied results of stainable development and combining the practice of the Islands and data obtained. Which are the bases of further discussion of the stainable development patterns of Island and important principle for the decision-making,management and control of littoral stainable development.

Abstract: Like on 6H-SiC substrates, 3C-SiC islands precipitation was found to be the initial stage of the VLS growth of 3C-SiC layers on 4H-SiC surfaces. This precipitation happens between 1100 and 1200°C with a heating rate of 2.8°C.s-1, without addition of propane. The islands size increases in a similar manner whether the final temperature increases (for a given heating rate) or the heating rate decreases (for a given final temperature). This enlargement can give rise to a complete cubic layer for the highest temperatures or the slowest heating rates. It is suggested that the carbon atoms involved in the enlargement process (after the nucleation) come from the graphite crucible.

Abstract: Twin-free 3C-SiC layers were recently obtained by Vapour-Liquid-Solid mechanism on a a-SiC(0001) substrate using Si-Ge melt. The formation of cubic layers is rather unexpected since growth from the melt is known to promote lateral growth and should thus give homoepitaxial layers. The study of the early stage of such growth, after a simple contact between the melt and the substrate (without adding propane), reveals the precipitation of 3C-SiC elongated islands upon the substrate surface. The chemical interactions inside the Ge-Si-C ternary phase diagram suggest an initial dissolution of the SiC seed in contact with a Ge-rich melt (below 1200°C). When the Si content of the melt subsequently increases upon heating, the dissolved carbon atoms precipitate on the seed surface under the form of 3C-SiC islands. When propane is added, these islands enlarge and coalesce to form a complete 3C layer.

Abstract: We report on the heteroepitaxial growth of 3C-SiC layers by Vapor-Liquid-Solid (VLS) mechanism on Si face 6H-SiC substrates, on-axis and 3.5° off. The Si-Ge melts, which Si content was varied from 10 to 50 at%, were fed by 3 sccm of propane. The growth temperature was varied from 1200 to 1600°C. It was found that 3C-SiC layers (either twinned or twinned free) form at low temperature while homoepitaxy is achieved at high temperature. The proposed growth mechanism involves the initial formation of 3C islands during the heating ramp (below 1200°C) and the dissolution of these islands when temperature increases. Geometrical aspects, such as the step density at the surface and the vertical component of the growth, are also considered to explain the difference observed between the on and off axis substrates.