9318749 Goldman Technical abstract: Two-dimensional electron states (2DES) in semiconductor microstructures exhibit unique properties associated with strongly correlated electrons. Such properties include one- dimensional edge states, Wigner crystallization, and single-charge carrier tunneling. The properties of the collective ground states of 2DES and size-quantized systems of few electrons, their excitations, edge states, and the quantum phase transitions will be studied experimenrally at very low temperatures and very high magnetic fields via magnetotransport, thermal activation, nonlinear transport, as well as by resonant and single particle tunneling experiments. Non-technical abstract: Ultra-thin layers of semiconductors can have significant potential applications in future high performance semiconductor devices. Such materials systems also allow the investigation of unique electronic phenomena which are particularly strikingly exhibited at very low temperatures close to absolute zero and in very high magnetic fields. The "quantum Hall effect" is one of the remarkable phenomena which exhibits highly unusual phenomena such as fractional electronic charge and highly ordered assemblies of electrons. The proposed experiments are designed to understand the broad theoretical concepts that underlie thses unique properties. In another experiment the transport of single electrons will be studied in specially designed ultrasmall semiconductor dots which are initially unoccupied by electrons. The approach is to measure the changes in electronic current as electrons are sequentially transferred into such a quantum dot. This process will be extended to ultralow temperatures and high magnetic fields and compared with recent theoretical predictions. ***
