Spin coating fabrication of thin film transistors using enriched semiconducting SWNT solution

Semiconducting single wall carbon nanotubes (SWNT) are excellent candidates for thin film transistor (TFT) applications. Major obstacles in developing low cost separation techniques for high purity semiconducting SWNTs have hindered their incorporation into many low-end functional devices. For low-end transistor devices a moderate ON/OFF ratio and performance is sufficient. A mix of single wall nanotubes with enriched semiconducting tubes can meet these needs. Using such 90% semiconducting enriched SWNTs, we have fabricated thin film transistors with a maximum 104 ON/OFF ratio. The device-manufacturing yield was low due to inconsistencies in the distribution of the SWNTs across the wafer. Increasing the density of the SWNTs in the channel using the drop casting method increased the device-manufacturing yield but decreased the performance. Conducting multiple spin coating processes is expected to increase the device-manufacturing yield without sacrificing device performance.