1st paper: Template-based carbon nanotubes and their application to a ﬁeld emitter
2nd paper: Controlled fabrication of Large Scale Aligned Carbon Nanotubes patterns by Photo Lithography
Purpose of research and emphasis/main topic of publication:
The aim of the first paper is to illustrate fabrication methods for large scale aligned carbon nano fiber/nanotube patterns on substrates. They used patterning metal-containing photoresists that was with conventional of black and white film which considered like a mask. The second paper was aimed to study the CNT as filed emitter device which obtained from anodic aluminum oxide (AAO) template of thin film in a silicon wafer. Controlling the growth ...view middle of the document...
The achievement of the second methodology was the pattern of metal precursor that was heated to remove the polymer matrix, then reduced by H2/Ar that produced metallic catalysts for the growth of carbon nanofibers/nanotubes. Those were aligned on the regions of photoresist and their growth achieved by the pyrolysis of acetylene with varying temperature and time that were approved by SEM and TEM figures.
The methodology of second research was divided into preparation, SEM observation after applying voltage and the observation of the morphology and the structure CNTs by field emission-scanning electron microscopy of and the high resolution transmission electron microscopy. The preparation of samples there were two main aluminum samples. Sample one was 12 micrometers (AL) thicker and suppurated in Si wafer, then electropolished to obtain mirror finish. While the second sample was a film 400 nanometer (ALNB) suppurated on a coated Si wafer by Nb which electropolished to obtain a smooth surface. Those samples were anodizing in a solution of oxalic acid and the DC anodized voltage was 40 V. The phosphoric acid was used to reduce the barrier layer by dipping the AAO template in it for 50 min. Throughout that time the pores enlarged around 70-80nm.
In 1st research paper, they succeed to align the carbon nanofiber patterns on the substrates and found that different parameters influenced the alignment such as the size and density of catalyst particles and the temperature of pyrolysis. They generated a large scale of carbon nanofiber and nanotube by the photomask fabrication directly obtained in photolithography which was a good step for the prototyping of them.
By the result and the observation of the morphology used in the second work. They succeed that after the pore widening of ALNB, their cross section showed at the bottommost of the AAO templates were deposited Co catalyst by electrochemical way and reduced in a gas mixture of 2% H2 and 98% are at 600 °C for 1 h. After that, the pyrolysis C2H2 catalyst caused the growth of CNTs at 650 °C which were overgrown on the AAO templates. They found no differences in the morphology of both samples. The diameters of the CNTs were depending on the pore diameter on the AAO template they were about the same. In addition the CNTs growths were straightened and improved the pore when the length of the pore increased in the template. Therefore the growths of CNTs were affected by the p presence of H2 in an AAO template. Co was the active catalyst for acetylene decomposition...