| This dissertation presents results of studies of ballistic electron transport in semiconductors and studies of an electron loop mirror. This research involves both the investigation of semiconductor physics and the design and development of novel electronic devices.; We have successfully made a device in which electrons travel ballistically for nearly 6 μm, which is the longest ballistic transport ever reported in vertical ballistic transistors. Based on the understanding of our devices, a current model has been developed to extract the mean free path of high energy electrons from the data obtained with different devices. A calculation of the mean free path including various scattering processes is in agreement good with the data.; We have used a modified Aharonov-Bohm ring fabricated from a GaAs/Al xGa1−xAs HEMT structure to demonstrate an electron loop. In this 4-terminal configuration we have simultaneously measured the reflection and transmission of electrons by the ring. The transmission signal shows mainly h/e oscillations (as a function of magnetic field) and rapidly shifts phase with variations in gate bias. On the other hand, the reflection signal oscillates at half the period, h/2e, and its phase does not change with gate bias. The natural insensitivity to random potentials of the reflection signal suggests that this principle may be applied to the design and operation of future nanoscale phase coherent devices that are otherwise extremely sensitive to local potential fluctuations. |
