The effect of elastic scattering due to impurities in the quantum waveguide is investigated with an exact calculation. It is treated as a one-dimensional scattering problem and any width effect is neglected.The method is applied to the quantum modulated transistor and the Aharonov-Bohm ring. The overall transmission of the structure is found to be distorted owing to the scattering, the extent of the distortion being not only dependent on the impurity potential strength, but also on the impurity positions. The cutoff frequency of the transistor affected by the scattering is also discussed.
In this letter, we report the catalytic synthesis of a large amount of straight carbon nanotubes using a transition-metal cobalt–nickel/zeolite catalyst. High-resolution transmission electron microscopy images show that they are well graphitized. Raman spectrum shows its peak at 1349 cm−1 (D band) is much weaker than that at 1582 cm−1 (G band). We believe that straight carbon nanotubes contain much less defects than curved nanotubes and might have potential applications in the future.
Initial growth process of carbon nanowalls synthesized by radical injection plasma-enhanced chemical vapor deposition Synthesis of high yield single helical carbon microsprings by catalytic chemical vapor deposition and an experimental investigation of their growth mechanism
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