Increasing Efficiency in Single-Walled Carbon Nanotube/n-Si Photodetectors by Voltage Doping

Single-walled carbon nanotube (SWCNT) ultrathin films were deposited on n-doped Si substrates provided with three electrodes for photoconductive measurements. Without illumination, the devices show good rectifier properties and holes mobility in the range 10 ⁵ cm ² /V·s, which makes them very promising for fast switching applications. Measuring the current voltage characteristics of the SWCNT film under illumination, an increase in the device performance is observed when a voltage V _G is applied to the third electrode. In particular, increasing V _G toward the breakdown region, an increase of more than ten times is recorded in the photocurrent and in the external quantum efficiency with respect to the values measured at V _G = 0. The experimental data are interpreted considering a hole doping of the SWCNT film by the action of the third electrode voltage V _G .