1 research outputs found
Photoresponse of a Single Y‑Junction Carbon Nanotube
We report investigation of optical
response in a single strand of a branched carbon nanotube (CNT), a
Y-junction CNT composed of multiwalled CNTs. The experiment was performed
by connecting a pair of branches while grounding the remaining one.
Of the three branch combinations, only one combination is optically
active which also shows a nonlinear semiconductor-like <i>I</i>–<i>V</i> curve, while the other two branch combinations
are optically inactive and show linear ohmic <i>I</i>–<i>V</i> curves. The photoresponse includes a zero-bias photocurrent
from the active branch combination. Responsivity of ≈1.6 mA/W
has been observed from a single Y-CNT at a moderate bias of 150 mV
with an illumination of wavelength 488 nm. The photoresponse experiment
allows us to understand the nature of internal connections in the
Y-CNT. Analysis of data locates the region of photoactivity at the
junction of only two branches and only the combination of these two
branches (and not individual branches) exhibits photoresponse upon
illumination. A model calculation based on back-to-back Schottky-type
junctions at the branch connection explains the <i>I</i>–<i>V</i> data in the dark and shows that under
illumination the barriers at the contacts become lowered due to the
presence of photogenerated carriers