Speaker
Description
Carbon nanotubes have long been attracted much consideration as novel materials that are potentially applicable for making a wide variety of nanoelectronic devices. Due to their remarkable electronic properties, carbon nanotubes have been considered to be intelligent material that could make revolution in optoelectronic science. In this research, we reported experimental results of photocurrent measurements in single-walled carbon nanotube (SWCNT) field-effect transistors (FETs) assembled by AC dielectrophoresis method. Our SWCNTs-FET devices were prepared from high purity SWCNTs dispersed in toluene and then aligned in 3 micron gaps of Pd/Pd and Pd/Al electrodes. By using high-frequency AC voltage, a sharp ended side of each pair of the electrodes was used to produce non-uniform electric field to contact a few individual SWCNTs to make conducting channel of FETs. I-V characteristics were taken in two different electrode contacts (Pd/Pd and Pd/Al) to create built-in bias potential due to metal contact work functions. The results showed that nonlinearity of I-V curves was found in Pd/Pd electrode. In contrast to Pd/Al electrodes, diode-like behavior was presented. Charge carriers in conducting channel can be tuned due to application of gate voltage and hence field effect mobility was calculated in order of $\: \text{10}^5 \: \text{cm}^2/\text{Vs} \:$ in individual SWCNT model. Photocurrent measurement was performed by using a board wavelength (200-2500 nm) light source. We found that photocurrent was increased by increasing light-source power up to 200 W due to electron-hole pair creation process in the semiconducting SWCNT (s-SWNTs). The relationship between photocurrent and light-source power was found to be exponential grow which is different from linearity in thin-film s-SWCNTs. Photoresponsivity of the detection was calculated up to 250 A/W while quantum efficiency was found as 380% at a fixed source-drain bias voltage. This study presents the fundamental fabrication along with the photoexcitation measurements in a semiconducting single-walled carbon nanotube field-effect transistor using simple and low cost technique. Our results indicate an important implication in future nanoelectronic devices.
