No abstract

No abstract

No abstract

Cobalt silicide formation has been studied using thin films of Co on Si wafers with different impurity contents in the metal and with thin or thick native oxide at the Co/Si interface. The incorporation of impurities into the film was controlled by changes of the pressure during Co deposition. Two RTP systems with two different annealing ambients and heat sources were used for silicidation. For Co films with low contaminant level, thin or thick native oxide can be dissolved and good quality CoSi2 is formed. For Co films with high impurity level in the presence of thick native oxide, the silicidation can be performed, delayed, or even inhibited, depending on film thickness and annealing conditions.

Diferentes materiais nanoestruturados à base de carbono, tais como nanotubos, nanofibras, nanomolas e nanooctopus, foram obtidos através do processo de deposição química de vapor. Tais experimentos foram realizados em um forno tubular e variações nos parâmetros experimentais permitiram a obtenção das diferentes nanoestruturas de carbono. Filmes finos de Ni e Cu foram depositados sobre substratos de SiO 2 /Si e empregados como catalisadores. O efeito de diferentes gases precursores de carbono, da temperatura de crescimento e do metal catalítico sobre as características do material final foi investigado por microscopia eletrônica de varredura, espectroscopia Raman e difratometria de raios X com ângulo rasante. O uso dos gases metano e acetileno levaram à formação de nanotubos de carbono para ambos os filmes metálicos, enquanto Ni parcialmente oxidado promoveu o crescimento de nanomolas. Estruturas do tipo octopus foram obtidas a partir do uso de cobre associado a um fornecimento relativamente restrito de metano.Different carbon nanostructured materials, such as nanotubes, nanofibers, nanosprings and nanooctopus, were grown by changing the metal catalyst and experimental parameters of the thermal chemical vapor deposition process. These experiments were performed using a tubular furnace and methane or acetylene as carbon feedstock gases. Thin films of Ni or Cu were deposited onto a SiO 2 /Si substrate and employed as catalysts. The effect of the growth temperature, metal catalyst and carbon gas precursor (methane or acetylene) on the final carbon nanoestructured material was studied by scanning electron microscopy, Raman spectroscopy and grazing incidence X-ray diffraction. Growth of multiwall carbon nanotubes (MWCNTs) was observed using both metal films and carbon precursor gases, whereas partially oxidized Ni films promoted formation of nanosprings. Experiments with reduced supply of methane resulted in octopus-like carbon nanostructures when a Cu film was used as a catalyst.Keywords: carbon nanotubes, carbon nanosprings, carbon nanooctopus, Chemical Vapor Deposition (CVD), metal catalysis IntroductionThe ability of carbon to form strong chemical bonds with itself (in different allotropic forms) and many other elements is responsible for the existence of a vast number of carbon-based materials and compounds. It makes carbon one of the most fascinating building blocks for synthesis of new structures with unique properties. As a consequence, a great variety of carbon nanostructured materials have been grown in many laboratories. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Among the different carbon nanostructures, nanotubes (CNTs) have received much attention due to their extraordinary electronic, mechanical, chemical, optical and other properties. Depending on their structural characteristics, CNTs can exhibit metallic or semiconductor behavior, thus being promising material for designing new nanoelectronic devices, such as field-effect transistors.1,2 Many other potential technological applications can be lis...

A novel multisampling time-domain architecture for CMOS imagers with synchronous readout and wide dynamic range is proposed. The architecture was implemented in a prototype of imager with 32x32 pixel array fabricated in AMS CMOS 0.35μm and was characterized for sensitivity and color response. The pixel is composed of an n+/psub photodiode, a comparator and a D flip-flop having 16% fill-factor and 30μmx26μm dimensions. The multisampling architecture requires only a 1 bit per pixel memory instead of 8 bits which is typical for time-domain active pixel architectures. The advantage is that the number of transistors in the pixel is low, saving area and providing higher fill-factor. The maximum frame rate is analyzed as a function of number of bits and array size. The analysis shows that it is possible to achieve high frame rates and operation in video mode with 10 bits. Also, we present analysis for the impact of comparator offset voltage in the fixed pattern noise.

No abstract

No abstract