In this article, a curriculum on the construction and maintenance of a high-performance computing cluster for students in engineering and science is presented. Laboratory sessions are an important part of this curriculum. Successive completion of the laboratory sessions automatically leads the student group to a homemade full-functioned cluster. Students are encouraged as they see their computing cluster working at the end of the curriculum. This curriculum can be of benefit to the students who are involved with computationally intensive simulations. ß
The purpose of this study is to investigate the effect of graphitization of carbon nanotube (CNT) films on their field emission efficiencies. CNT films were prepared by microwave plasma-enhanced chemical vapor deposition (MPCVD) method. Transmission electron microscopy images reveal the center hollowness and multiwalled structure of a CNT. The tip-growth mechanism of the CNTs prepared by MPCVD is confirmed by the nickel particles enclosed at the tips of the CNTs. The intensity ratio of IG∕(ID+IG) under the Raman spectrum was defined to characterize the degree of graphitization of the CNTs. At any methane flow ratios [CH4∕(H2+CH4)], the CNT graphitization increases with the microwave power. Also, the CNT graphitization increases with the CH4 flow ratio and begins to drop at the flow ratio of 15%. It is mainly attributed to the relative concentration of carbon radicals in the hydrocarbon-based plasma. Enhancement of the graphitization of CNT emitter array leads to the decrease of the threshold field and the increase of the field-controlled current density consistently. This consistency suggests that higher concentration of sp2 bonding enhances conductivity. Therefore, the field emission efficiency of the CNTs increases with the CNT graphitization. At the microwave power of 1200W and the methane flow ratio of 15%, the graphitization intensity ratio is 0.637. The optimal threshold field and field-controlled current density at the field of 3V∕μm are 1.38V∕μm and 8.934mA∕cm2, respectively.
The temporal saturation effects of the critical dimensions of nanoscale contact holes are investigated by a two-dimensional reaction–diffusion simulator for the chemical shrink techniques of nanolithography. Models included with the simulator are the crosslinking reaction of water-soluble polymers and crosslinkers, the diffusion of photoacids, and the inactivation of photoacids. Within the the statistical errors of the experimental data, the simulation critical dimensions agree with the experiment for baking temperatures over 105°C and for all baking times. It is found that the temporal saturation of the contact holes' critical dimensions can be explained by the photoacid inactivating reaction included in the simulator.
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