Photoconductivity characterization of single-walled carbon nanotube phototransistors

Understanding electronic interactions in nano-scale devices is of crucial importance because only through furthering the knowledge of their electronic operations can progress be made in the field. Carbon nanotube devices, the current nano-device leaders, are prime examples of circuits that can benefit from further electronic studies. Without a better understanding of the entire device operation, the success of carbon nanotube electronics may be limited to the laboratory.; The fundamental issue that needs to be addressed is the fact that on a nanometer scale, everything the device is in contact with will play a role in its operation. A carbon nanotube cannot be thought of as the only subject of a carbon nanotube device study. Only by examining the interactions with the materials surrounding the nanotube can a complete model be prepared.; In this dissertation, it is shown that the metal - nanotube interface plays a large role in the structure and even the existence of electronic properties measured in nanotube devices. By performing photocurrent measurements on carbon nanotube devices it was discovered that they have the ability to function as nanoscale phototransistors with strong dependencies on contact materials. With the proper contact materials, strong photocurrent amplification is possible, making carbon nanotube phototransistors very sensitive photodetectors.; Analysis of the carbon nanotube phototransistor's photoconducting spectra shows signs of tunneling-assisted photoexcitation. The spectral photoconductivity is heavily dependant upon the choice of contact material, showing robust photoconductivity for some contact materials, while showing negligible photoconductivity for others. It is concluded that by changing the metal - nanotube interfaces, one can tailor the nanotube device properties.