Field electron emission from diverse carbon nanostructures: Comparative characterization and applications

Since their discovery in 1991 Carbon Nanotubes have been widely studied because of the unique electronic properties that they posses. They have emerged as promising candidates as Field Emission (FE) sources because of their ability to sustain high current densities at low electric fields. They have wide applications in flat panel displays, electron guns, ion sources in lamps etc. The possible use of carbon nanotubes as cold cathodes for space mass spectrometry has not yet been studied though they appear to be ideally suited to be low power sources for ionization. The primary objectives of this dissertation was to find nanostructures that had high stabilities and could be possible electron sources in mass spectrometers. These studies resulted in certain interesting phenomenon which consequently developed into independent projects under the broad umbrella of Field emission from nanostructures: characterizations and applications.; Multiple samples were characterized based on their field emission properties in Task 1, and during these studies the unusual phenomenon of transfer of oriented arrays of multi walled carbon nanotubes (MWNT) from one surface onto another was discovered and filed as a patent in November 2004. The single walled carbon nanotubes (SWNT) that were also studied in Task 1, do not have the instabilities that MWNT (which led to the transfer) have, but, their comparatively high threshold electric fields are a disadvantage. Thus in Task 3, the work function tuning of SWNT paper by double layer electrochemical charge injection was explored. Significant change in the work function was seen.; Cathodoluminescence (CL) from organic multilayers is not as widely studied a subject as Electroluminescence (EL). In Task 4, we studied CL resulting from the electron impact ionization inside organic multilayers. The results show that this phenomenon can be very promising for organically pumped lasers and for charge multiplication in organic light emitting diodes. In the last Task, a suitable nanostructure which could be used as the electron source in space applications was found. Unusual MWNT yarns were found to have the required low threshold electric fields, high current densities and excellent stability that is necessary for a good ionization source.