| This thesis reports the findings of ultrafast electrical measurements performed on bulk semiconductors, metal films, and two-dimensional electron gas (2DEG) systems. The cornerstone of the research presented here is a simple photoconductive element called an Auston switch. By integrating these switches into waveguides, one can generate, guide, and detect electrical transients on a picosecond time-scale. In this thesis, Auston switch based waveguides are applied to terahertz spectroscopy and ballistic electron transport.; First, a room temperature waveguide probe capable of distinguishing semiconductors of various doping densities is demonstrated. It was found that this technique may offer a non-invasive method for measuring semiconductor resistivity. The same probe also has the ability to distinguish metal films of varying thickness and composition.; Using similar waveguides with a modified experimental setup, spectroscopic measurements of dipolar resonances in two-dimensional electron gas (2DEG) systems in cryogenic systems were performed. Using this technique, the magnetoplasmon resonance at frequencies up to 500GHz, and bath temperatures down to 50mK in a dilution refrigerator was detected in a 2DEG.; Finally, picosecond time resolved measurements of ballistic electron transport are reported. This experiment was carried out by delivering picosecond electrical pulses to the emitter of a transverse magnetic focusing device and time-resolving the collector voltage. These findings represent the shortest time-scale on which direct electrical excitation and detection of ballistic electron transport has been observed and will hopefully stimulate future research in this largely unexplored transport regime. |
