| This thesis presents various experimental results from electron transport measurements of two-dimensional electron gases (2DEG's). The interactions between localized, effectively zero-dimensional regions of 2DEG ("quantum dots") are studied by observing changes in current through double-dot systems. When the dots are arranged in series, it is found that the current depended sensitively on the alignment of the quantized energy states of the individual dots. It is also found that the 2DEG device used in these experiments---a unique gated-Hall-bar heterostructure---is prone to forming extra unintentional dots in parallel with the intended, lithographic dot. Using a different device, we measure nonlinear electron scattering between neighboring Quantum Hall edge states. The interedge-state bias is induced and the resulting interedge current measured using quantum point contacts (QPC's) in a unique "semi-QPC" arrangement. The interedge current as a function of bias shows behavior similar to that of a backward diode, with a sharp upturn at a forward bias equal to the LL splitting, and we develop a "Landau Level diode" model to account for the main features. In particular, we find that electron scattering between spin-split edge states can, by virtue of its need to flip spin, interact with the Ga and As nuclei surrounding the 2DEG and polarize them, a process called dynamic nuclear polarization (DNP). We also propose a new model of the 2DEG edge which combines the effects of exchange and self-consistent electrostatics. |
