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 ${\text{10}}^{5}\,{\text{cm}^2/ \text{V}}$ ·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 $V_G$ .