One class of nanoscale materials which has attracted tremendous attention is the quasi-onedimensional
(Q1D) system since the revolutionary discovery of carbon nanotubes in 1991. Enormous
progress has been achieved in the synthesis, characterization, and device application of the Q1D
systems. These structures with high aspect ratio (i.e., size confinement in two coordinates) offer better
crystallinity, higher integration density, and lower power consumption. And due to a large surface-tovolume
ratio and a Debye length comparable to the small size, they demonstrate superior sensitivity to
surface chemical processes. In addition, their size confinement renders tunable band gap, higher
optical gain and faster operation speed.