Light detection by carbon nanotube circuit with strong intertube conduction

This manuscript reports the application of carbon nanotube (CNT) circuits as visible light sensors. The CNT circuits are made of vertically aligned multiwalled CNT (MWCNT) forests, with electrodes covered by silver paste, thus the electron conduction between electrodes was dominated by the intertube conduction. The linear current-voltage curves of these CNT circuits reveals typical circuit resistivity on the order of 10^-3 Ωm if taking the whole macroscopic volume of the CNT circuit into account. The CNT circuit resistivity was found to decrease with CNT height. On the other hand, the photocurrent was found to be sensitive to the illumination locations, and the largest photocurrent appears when the light spot was located at one electrode. In addition, the photocurrent varies with the applied voltage between electrodes, and it starts to saturate at about ±1.5 V for most CNT circuits.