- Carbon nanotubes,
Carbon nanotubes (CNTs) are promising nanomaterials for high frequency applications due to their unique physical characteristics. CNTs have a low heat capacity, low intrinsic capacitance, and incredibly fast thermal time constants. They can also exhibit ballistic transport at low bias, for both phonons and electrons, as evident by their fairly long mean free paths. However, despite the great potential they present, the RF behavior of these nanostructures is not completely understood. In order to explore this high frequency regime we studied the microwave (MW) and terahertz (THz) response of individual and bundled single wall nanotube based devices. This thesis is an experimental study which attempts to understand the high frequency characteristics of metallic single walled carbon nanotubes, and to develop an ultra-fast and sensitive direct THz detector.
First, the appropriate high frequency detector background is introduced. CNTs previously measured behavior draws similarities to two types of detectors: diode and bolometer. Therefore, our CNT devices are geared towards those designs. Second the fabrication process of devices is reviewed. UV lithography is used to pattern THz coupling log periodic antennas, on top of which CNTs are deposited by using a dielectrophoretic process. Third, the fabricated devices are tested at DC, MW, and THz frequencies. All of these measurements are done as a function of temperature, power, and frequency. Finally, the physical processes that give rise to the diode and bolometric detections at MW and THz detection at different temperatures and under different bias regimes (i.e. low and high) are explained.
Available at: http://works.bepress.com/enrique_carrion/1/